Opinion for the court filed by Circuit Judge RANDOLPH.
Dissenting opinion filed by Circuit Judge HARRY T. EDWARDS.
RANDOLPH, Circuit Judge:
Some opaque containers induce assumptions about their contents. Refrigerators contain food. Under the hoods of automobiles are engines. These are predictions, based on experience. Narcotics officers have their own specialized experience and training. Detective John Centrella saw a small rectangular block wrapped in silver duct tape. To the uninitiated, the object's outward appearance said nothing about its contents. To Detective Centrella, the size, shape and wrapping of the object signified one kilogram of illegal narcotics. The question is whether Pedro Jolio Prandy-Binett's possession of the object, together with other information, gave the detective probable cause to arrest him.
Detective Centrella and another narcotics detective were on duty at Union Station, meeting trains arriving from New York City, a "source city" for drugs. As they watched departing passengers, their attention was drawn to an individual walking through the station faster than the others and trying to get around them. When the individual— Prandy-Binett — made eye contact with the detectives, who were in plain clothes, he moved even more quickly toward the exit. The detectives approached him and identified themselves. After telling the officers he had come from New Jersey, Prandy-Binett produced a one-way train ticket, purchased with cash, showing that his trip originated at Penn Station, New York City. After saying he lived in Washington, D.C., he handed the officers a driver's license showing Hyattsville, Maryland, as his residence. Detective Centrella's suspicions, aroused by these possible inconsistencies, were heightened by the cloth "tote" or "gym" bag Prandy-Binett car ried on his shoulder. Prandy-Binett reported having spent a week working in New Jersey. Yet his only luggage was the small bag, which did not appear full. Asked whether the bag contained drugs or guns, Prandy-Binett said no. Detective Centrella then requested permission to search the bag. Prandy-Binett replied that he did not have to consent and that the bag contained only clothing. He took the bag from his shoulder, placed it on the ground, knelt down (as did the detective next to him), unzipped the bag and began pulling out a pair of blue jeans. This action uncovered a miniature shopping bag lying on its side, deep purple in color, a "perfume or a cologne bag" from Elizabeth Taylor Perfume. Unprompted, Prandy-Binett said, in evident reference to the perfume bag, "this is a gift." As Prandy-Binett continued to manipulate the blue jeans, a portion of a rectangular block, wrapped in silver duct tape, slid out of the perfume bag. Believing the block to contain illegal drugs, Detective Centrella handcuffed Prandy-Binett, examined the wrapped object further, and seized it and the gym bag. A later field test on the contents of the wrapped block revealed cocaine.
A single-count indictment charged Prandy-Binett with possession with intent to distribute 500 or more grams of cocaine, in violation of 21 U.S.C. § 841(a)(1), (b)(l)(B)(ii). After an evidentiary hearing, the district court held that the detectives had violated Prandy-Binett's Fourth Amendment rights. The government sought to justify the seizure and search of the wrapped block as incident to a valid arrest. The district court found that Prandy-Binett was arrested immediately after the detectives observed part of the wrapped block. At that point, the court held, the detectives did not have probable cause to believe Prandy-Binett had committed an offense. The exclusionary rule therefore demanded suppression of the cocaine as the fruit of the illegal arrest. 774 F.Supp. at 28. Relying on the testimony of the government's expert, the court stated "that the proper approach" would have been "to investigate further, not to immediately arrest the defendant." Id. At a status call after the district court issued its written opinion, the government acknowledged that it could not proceed without the suppressed evidence, and the court dismissed the indictment. This appeal followed.
Somewhere between " 'less than evidence which would justify . ' conviction" and "more than bare suspicion," probable cause is satisfied. Brinegar v. United States, 338 U.S. 160, 175, 69 S.Ct. 1302, 1310, 93 L.Ed. 1879 (1949) (citation omitted). The precise point is indeterminate. We are concerned not simply with probabilities, but with conditional probabilities: if one event occurs, how likely is it that another event will occur? This is why the detectives' observations up to the time the block slipped out of the perfume bag cannot be disregarded. It is why in similar eases we ask, although sometimes tacitly, what is the probability that a train passenger arriving at Union Station from New York City will be carrying cocaine? Quite low, we trust, despite New York's status as a source city for narcotics. Is the probability increased if the passenger moves quickly through the station after leaving the train? Greater if the passenger also gives apparently deceptive answers when the police question him? Greater still if the passenger opens his bag and refers to a package wrapped in duct tape inside a fancy perfume bag as a "gift?" Neither courts nor law enforcement officers, nor anyone else for that matter, can quantify any of this. A mathematician could not perform the calculations because there is no way of assigning probabilities to the individual events. The information is simply unavailable, as will doubtless be true in every Fourth Amendment case. Still, we are convinced that, up to the sighting of the duct tape package, the conditional probability was low, much too low to have satisfied the Fourth Amendment in light of the interests it protects.
The case thus comes down to the detectives' inference of narcotics from the appearance of the wrapped block, and the extent to which that inference enhanced the probability of Prandy-Binett's possessing drugs. We put the question in these terms because "probable cause" is evaluated not only from the perspective of a "prudent man," Gerstein v. Pugh, 420 U.S. 103, 111, 95 S.Ct. 854, 861, 43 L.Ed.2d 54 (1975); Beck v. Ohio, 379 U.S. 89, 91, 85 S.Ct. 223, 224, 13 L.Ed.2d 142 (1964), but also from the particular viewpoint of the officer involved in the search or seizure. See, e.g., Texas v. Brown, 460 U.S. 730, 742-43, 103 S.Ct. 1535,1543, 75 L.Ed.2d 502 (1983) (plurality opinion); United States v. Cortez, 449 U.S. 411, 418, 101 S.Ct. 690, 695, 66 L.Ed.2d 621 (1981); United States v. Ortiz, 422 U.S. 891, 897, 95 S.Ct. 2585, 2589, 45 L.Ed.2d 623 (1975); Johnson v. United States, 333 U.S. 10, 13, 68 S.Ct. 367, 368, 92 L.Ed. 436 (1948); United States v. Davis, 458 F.2d 819, 821-22 (D.C.Cir.1972). See generally 1W. LaFave, Search and Seizure § 3.2(c) (2d ed. 1987). Law enforcement officers naturally reach conclusions based on their training and experience. In cases of searches or seizures without warrants, the court's role is to decide whether the officer's inference from the facts was "reasonable," United States v. Ortiz, 422 U.S. at 897, 95 S.Ct. at 2589. This depends on information showing the officer's accumulated knowledge of criminal activity, information that must be in the record if it is to be considered.
Upon seeing the kilo-sized rectangular package wrapped in silver duct tape sticking out of the perfume bag, Detective Centrella and his partner immediately concluded that it held narcotics. Detective Centrella testified: "As soon as I saw that, in my mind, that's drugs." The record firmly supports the detective's inference.
There was first the block's bulk. The weight of consumer goods in this country is usually described in pounds and ounces. Perhaps because of foreign influence, the weight of illicit narcotics is usually measured — in statutes and on the street — in terms of the metric system. The evidence showed that in the drug trade, a kilogram of cocaine or heroin is a standardized unit of exchange, commonly referred to as a "kilo brick" or simply a "kilo." (A kilogram equals 2.2046 pounds.) Detective Centrella was quite familiar with the bulk of packages containing one kilogram of cocaine. During his 20 years of service, he personally had seized 100 such kilos and had seen many more. Both Detective Centrella, and his partner, an experienced narcotics detective who had undergone training at the Drug Enforcement Administration, thus had good reason for believing that the wrapped block in Prandy-Binett's gym bag was about the size of a package containing one kilogram of cocaine or heroin.
The second consideration was the rectangular shape of the object. The portion protruding from the perfume bag was consistent with what the detectives knew to be the standard configuration, the typical "kilo brick." The bag itself, roughly four inches wide and between six and ten inches deep, was the right size for holding a kilo of narcotics so packaged. The brick-like shape of the object thus further alerted the detectives, in light of their training and experience, to the possible presence of narcotics.
The third factor was wrapping — silver duct tape (over plastic). Duct tape is attractive to traffickers because fingerprints are difficult to lift from its surface and because some criminals believe — erroneously—that it masks the odor of the drugs from police dogs. Detective Centrella testified that he had seen "several hundred" packages wrapped in silver duct tape similar in appearance to the one in Prandy-Binett's bag. Every one contained contraband. He also reported that approximately 95 percent of the kilogram-sized quantities of cocaine he had seized in his career were so packaged. The detective who accompanied Detective Centrella, and the government's expert witness, also had extensive familiarity with duct-tape packages of narcotics. Detective Centrella's experience replicates that of narcotics agents in New York City. The agent in United States v. Barrios-Moriera, 872 F.2d 12, 17 (2d Cir.), cert. denied, 493 U.S. 953,110 S.Ct. 364, 107 L.Ed.2d 350 (1989), "had participated in the seizure of three or four hundred separate kilos of cocaine," which were typically "wrapped in some variety of tape." The Second Circuit therefore held that "the rectangular package, measuring a certain size, wrapped in duct tape" proclaimed its illicit contents, so much so that the agent legally seized it without a warrant as contraband in plain view. Id.
To Detective Centrella the wrapped block thus conveyed the message "one kilo of narcotics" just as surely as if the words were written on the tape. The circumstances leading up to the arrest and the incongruity of the crudely wrapped block inside the fancy perfume bag, together with Prandy-Binett's unsolicited disclaimer "This is a gift," must have confirmed what the detective saw in his mind's eye. The record shows that the detective had a solid foundation from which to evaluate relative frequency, to judge the percentage of times such packages hold narcotics. Contrast Robbins v. California, 453 U.S. 420, 428, 101 S.Ct. 2841, 2846, 69 L.Ed.2d 744 (1981) (plurality opinion). Of the hundreds of packages of this type Detective Centrella had seen in his 20 years as a narcotics officer, every one contained drugs. Not once, in all his years as a narcotics officer, had he encountered a duct-taped package containing something other than drugs. No evidence indicated with what frequency, if any, packages of such bulk and configuration -with the same sort of wrapping as Prandy-Binett's held other material. While it is doubtless safe to assume there are such innocent packages, we — unlike Detective Centrella — have no basis, no foundation derived from experience, to make a judgment about their relative frequency anywhere, let alone at Union Station hidden in a bag carried by a passenger departing from New York who seemed to be giving deceptive answers to police questions. We cannot say exactly how probable it was that the block contained drugs, but we are convinced that it amounted, at the least, to a " 'fair probability'" Prandy-Binett was committing an offense. United States v. Caroline, 791 F.2d 197, 201 (D.C.Cir.1986) (quoting Illinois v. Gates, 462 U.S. 213, 238, 103 S.Ct. 2317, 2332, 76 L.Ed.2d 527 (1983)).
The district court stated that in answer to its hypothetical about a person of the judge's description carrying a duct-taped package in Union Station, "both arresting officers testified that no arrest would have been made." 774 F.Supp. at 28 n. 3. There is a bit more to it. The government's expert, after first saying he would arrest the person, said that on second thought he would perform a field test first and then make the arrest. Context makes it uncertain what the expert meant by "arrest." His second thought seemed to be that he would first place the person in custody and, after determining which illicit substance the package contained, make a formal arrest either for possession of cocaine or heroin. The question was not put to Detective Centrella. In any event, we do not view the court's hypothetical as an irresistible counter-example. The detective's partner, who said he would not make an arrest without investigating further, was asked only what he would do if a person fitting the judge's description were "walking" through the station carrying the wrapped block. None of the other circumstances was included — the passenger's arrival from New York City, his manner of walking quickly through the station and speeding up when he learned he was being watched, his apparently deceptive answers to the detectives' questions, the carrying of the block inside a perfume bag in a gym bag too small to accommodate much clothing or other personal effects. The prosecutor, in a follow-up question, tried to expand the hypothetical to include these circumstances, but the court sustained an objection. Furthermore, the court's hypothetical says nothing whatever about relative frequency, an essential factor in any evaluation of probable cause. As we have said, when one asks how often people carry duct-tape-wrapped packages of this size containing something other than drugs, the record suggests the answer never. While we sense that this is an overstatement, intuition cannot overcome the hard evidence of experienced detectives who have encountered hundreds of such objects.
Although not decisive, it is worth noting that in assessing probable cause the Supreme Court too has credited police officers' inferences about the contents of an object from its distinctive packaging. In Texas v. Brown, 460 U.S. 730, 103 S.Ct. 1535, 75 L.Ed.2d 502 (1983) (plurality opinion), a police officer believed from his experience that "an opaque, green party balloon, knotted about one-half inch from the tip" he spied in plain view in a suspect's car was likely to contain narcotics. See 460 U.S. at 733-34,103 S.Ct. at 1538-39. The plurality in Brown held that the officer's inference from the characteristic appearance of the balloon, when combined with other signs of drug paraphernalia spotted in the car, provided probable cause to seize the balloon, id. at 742-43, 103 S.Ct. at 1543, a conclusion all nine members of the Court joined. See id. at 746, 103 S.Ct. at 1545 (Powell, J., concurring in the judgment); id. at 750,103 S.Ct. at 1547 (Stevens, J., concurring in the judgment). See also Robbins v. California, 453 U.S. 420, 427, 101 S.Ct. 2841, 2846, 69 L.Ed.2d 744 (1981) (plurality opinion); Arkansas v. Sanders, 442 U.S. 753, 764 n. 13, 99 S.Ct. 2586, 2593 n. 13, 61 L.Ed.2d 235 (1979); Henry v. United States, 361 U.S. 98, 104, 80 S.Ct. 168, 172, 4 L.Ed.2d 134 (1959). This court also has relied upon the demonstrated expertise of police officers in recognizing distinctive packaging used in the drug trade for smaller quantities. We have credited officers' recognition of: "a package resembling narcotics," United States v. Thornton, 733 F.2d 121, 127 (D.C.Cir.1984); a distinctive "brown 'change-type' bag," United States v. Russell, 655 F.2d 1261, 1262-63 (D.C.Cir.1981), modified, 670 F.2d 323 (D.C.Cir.), cert. denied, 457 U.S. 1108, 102 S.Ct. 2909, 73 L.Ed.2d 1317 (1982); a rectangular tinfoil packet, United States v. Thomas, 551 F.2d 347, 348 (D.C.Cir.1976) (per curiam); a "cream-colored envelope," United States v. Brown, 463 F.2d 949, 950-51 (D.C.Cir.1972); and an unsealed brown envelope, United States v. Wheeler, 459 F.2d 1228, 1229 (D.C.Cir.1972). See also United States v. Berry, 463 F.2d 1278, 1284-85 (D.C.Cir.1972) (distinctive appearance of small packages used by gamblers to transport numbers slips). In each of these cases, as in this one, there was "evidence of record" describing the arresting officer's experience with the particular packaging.
The district court was evidently troubled by the fact that without further investigation (presumably a field test), the officers could not know whether Prandy-Binett's crime was possession of heroin or possession of cocaine. See 774 F.Supp. at 28. We do not share the court's concern. It is hard to see how a field test could be conducted without seizing the block and opening it, actions which themselves would presumably require probable cause. If officers have probable cause to go that far, we do not understand why they would not also have probable cause to arrest the person possessing the item before field testing it. Furthermore, the court's theory proves too much. If Prandy-Binett's perfume bag held clear ziplock bags containing white powder, the detectives also would not have been sure whether he possessed cocaine or heroin (or some innocuous substance). Yet that cannot be a reason for finding no probable cause. See United States v. Jacobsen, 466 U.S. 109, 121-22, 104 S.Ct. 1652, 1660-61, 80 L.Ed.2d 85 (1984). It is simply not the law that officers must be aware of the specific crime an individual is likely committing. See, e.g., United States v. Anderson, 923 F.2d 450, 457 (6th Cir.), cert. denied, — U.S.-, 111 S.Ct. 1633, 113 L.Ed.2d 729 (1991); United States ex rel. Frasier v. Henderson, 464 F.2d 260, 263 (2d Cir.1972). It is enough that they have probable cause to believe the defendant has committed one or the other of several offenses, even though they cannot be sure which one. The police may arrest an armed individual running from a store in the dead of night while the burglar alarm is sounding, even though they cannot be certain whether the suspected crime is attempted burglary, burglary, attempted robbery, robbery or unlawful possession of a firearm.
The orders of the district court suppressing the evidence and dismissing the indictment are reversed.
So ordered.
. Prandy-Binett testified that the detectives forced him to unzip the bag. In light of its disposition of the suppression motion, the district court found it unnecessary to decide whether the defendant voluntarily opened his bag. See United States v. Prandy-Binett, 774 F.Supp. 25, 26 n. 1 (D.D.C.1991). We intimate no view on the subject.
. Apparently both parties and the district court (see Prandy-Binett, 774 F.Supp. at 28 n. 2) believed that if Prandy-Binett was lawfully arrested, no further constitutional problem arose from the officer's warrantless seizure and later search of the wrapped block. Compare United States v. Chadwick, 433 U.S. 1, 15, 97 S.Ct. 2476, 2485, 53 L.Ed.2d 538 (1977); United States v. Six Hundred Thirty-Nine Thousand Five Hundred and Fifty-Eight Dollars in United States Currency, 955 F.2d 712, 717-18 (D.C.Cir.1992). The idea may be that the package itself could not "support any reasonable expectation of privacy because [its] contents can be inferred from [its] outward appearance.'' Arkansas v. Sanders, 442 U.S. 753, 764 n. 13, 99 S.Ct. 2586, 2593 n. 13, 61 L.Ed.2d 235 (1979), overruled, California v. Acevedo, - U.S. -, 111 S.Ct. 1982, 114 L.Ed.2d 619 (1991). See generally United States v. Williams, 822 F.2d 1174, 1181 (D.C.Cir.1987). Given the unanimity of views of this subject, we see no reason to pursue it further.
.Thus courts often refer to the need to consider "the totality of the circumstances" in evaluating probable cause. See, e.g., Illinois v. Gates, 462 U.S. 213, 230-38, 103 S.Ct. 2317, 2328-32, 76 L.Ed.2d 527 (1983); United States v. Chin, 981 F.2d 1275, 1278 (D.C.Cir.1992); United States v. Rodney, 956 F.2d 295, 298-99 (D.C.Cir.1992).