Forty-eight Americans were murdered in Mexico during the first six months of 2010 - a deadly pace that appears likely to exceed any previous year of homicides on record, according to the Houston Chronicle's analysis of the U.S. State Department's death registry. The tally doesn't include two Texans reported killed Sept. 30 in separate incidents in isolated areas of Tamaulipas, where the terrorist group known as the Zetas has been warring with their Gulf Cartel rivals in communities all along the Southeast Texas border. A college freshman from Brownsville, Jonathon William Torres Cazares, was shot and killed after authorities say his public bus got hijacked on a highway in Tamaulipas. 'He was 18 years old and traveling in Mexico visiting his family,' according to a statement issued by Leticia 'Letty' Fernandez, a spokeswoman for the University of Texas at Brownsville and Texas Southmost College. 'Our thoughts go out to his family and friends.' Meanwhile, David Michael Hartley, 30, of McAllen, was reported to have been shot in the head by a boatload of armed men while jet skiing on the Mexican side of the binational Falcon Reservoir, shared by Texas and Tamaulipas. His body has not yet been recovered. State Department data shows at least three other Americans were slain this year in Tamaulipas. But no details were available. In much of Tamaulipas, the news media is no longer reporting on crime because of threats and violence against journalists carried out by drug traffickers. American killings in Mexico have risen steadily since 2007, when drug violence first began to rage out-of-control in border cities like Nuevo Laredo and Tijuana and later spread to Ciudad Juarez, currently ranked as one of the most dangerous cities in the world. Most homicides this year occurred in border states, like Chihuahua and Baja California, the analysis of State Department data from mid-2002 to mid-2010 shows. Last year, 80 homicides of U.S. citizens were reported in Mexico, compared to 57 in 2008 and 35 in 2007. At least 13 Americans have been slain in Ciudad Juarez in 2010, including an employee of the U.S. Consulate, Lesley Enriquez, 35, and her husband, Arthur Redelfs, 34. Jorge Salcido, the Mexican husband of another consulate employee, was killed minutes before the others in a coordinated attack on their two cars. Enriquez worked in the citizen services, the section of the busy Juarez consulate that provides assistance to U.S. crime victims and their families and generally 'offers assistance to Americans in need,' said a spokesman for the U.S. Embassy in Mexico City. She said she could not comment on other 2010 murder cases involving Americans for privacy reasons. State department homicide statistics reveal only part of the story: Many killings abroad never get reported. Three U.S. citizens -a bridegroom, his brother and his uncle, all from New Mexico - were reported by Mexican authorities to have been abducted during a May wedding at the El Seor de la Misericordia Catholic Church in Juarez. Their bodies were later found dumped in a pickup truck, but those three homicides do not appear to be included in the registry. The State Department refuses to reveal the names of the victims. Nor does the department usually comment on the status of the homicide investigations, though consular officials are required to monitor investigations abroad that involve U.S. citizen victims and communicate with families. The policy can lead to ambiguous and even conflicting information. In a warning issued earlier in 2010, for example, the U.S. State Department specifically instructed Americans to avoid Gomez Palacio and other cities in the state of Durango because of 'sharp increases in violence.' The warning said four U.S. citizens had been murdered in Gomez Palacio in 2009-2010. However, the state department's own registry shows only three homicides there. One of the three victims was a California school board member, Roberto Salcedo, shot by gunmen who stormed a restaurant after Salcedo went to visit his wife's family during the Christmas holidays in Mexico last year. Many more killings of Americans have been reported in Chihuahua state, which includes Ciudad Juarez and borders El Paso. Sixteen U.S. citizens have been reported slain there so far in 2010 - 13 died in Juarez where an armed conflict between warring cartels has resulted in the loss of nearly 7,000 lives since 2008. Few U.S. murder cases appear to have been resolved, though details are unavailable. Mexican authorities did identify a suspect in the three consular-related killings in Juarez in March. He was recently extradited to the United States and arraigned in a closed hearing in a San Antonio federal court. But charges against him remain sealed. lise.olsen@chron.com XXX - End of Story3D 