Give U.S. Attorney Ron Machen time to probe Vincent Gray's campaign The malcontents shout at Machen: "Remove the cloud hanging over the city! Charge the mayor or close the case! Show us what you've got! I say, instead: "Mr. U.S. Attorney, take whatever time you need to get it right. If that requires many months or even years, as recent court developments suggest, then so be it. Little is more important than identifying and punishing delinquents who corrupted the electoral process at the foundation of our democracy. If that reaches to the mayor, then he needs to be brought to account. If his name is cleared instead, then we need to be sure it wasn't because the effort was done with undue haste. The fact is that these types of investigations take a long time. The federal corruption inquiry that put former Prince George's county executive Jack Johnson behind bars took six years. Compared with that, Machen's investigation is moving briskly. Three Gray campaign aides have pleaded guilty to felonies and agreed to cooperate. Moreover, Machen and his team have to interview numerous people who worked on the campaign - and perhaps re-interview them. They have many documents to examine. According to several credible accounts, the U.S. attorney faces resistance from potential witnesses who might want to protect the campaign and the mayor. Machen also needs to be wary of people who might lie or exaggerate to discredit Gray. "What you hear is that it's taking too long, but I don't find the length unusual," said Roscoe C. Howard Jr., a partner at Andrews Kurth who had Machen's position from 2001 to 2004. The cases are hard. You'll have people who are reluctant because of loyalty issues. You'll have people who are overeager because of resentment issues. My guess is they've got just tons of paper to go through," Howard said. Gray has denied he was involved in any wrongdoing but won't talk about the case while the investigation is underway. The prospect that it will last at least until spring has strengthened this month, as sentencing was postponed until March for two campaign aides who have pleaded guilty. They are Jeanne Clarke Harris, a communications consultant for Gray's campaign, and Thomas W. Gore, his assistant campaign treasurer. In both cases, sentencing was delayed because their cooperation with Machen was not completed. Machen's work also is slowed by the fact that a central figure in the case, businessman Jeffrey Thompson, apparently has not cooperated so far. Thompson has not been charged. But The Washington Post has reported that Thompson is the person described in court papers as having supplied $650,000 in undocumented contributions to Gray's campaign. According to several lawyers and other observers familiar with the investigation, Machen's strategy almost certainly is to build a sufficiently strong case against Thompson so he agrees to become a witness for the state. In that case, the thinking is, he could lead Machen to Gray or other people around the mayor. Of course, if it turns out Thompson didn't do anything wrong, then it might be there's no case against Gray, either. Either way, Thompson has retained an attorney, Brendan V. Sullivan of Williams and Connolly, who is famous for not cutting plea deals with prosecutors. He would rather go to trial, a prospect that surely would extend the case into 2014. Sullivan is also famous for not talking to the media and stuck to that policy with me. One bright spot for the city is the widespread feeling that Gray has been performing pretty well as mayor, after a rocky start, even if he won the office through a partly crooked campaign. "By all accounts, he's doing a good job," Board of Trade chief executive Jim Dinegar said. As a result, Dinegar is less worried about Machen's pace than he was a couple of months ago. It remains a significant concern because it hasn't been resolved. But it is not the drag on the city that it was earlier in the investigation," Dinegar said. Machen should aggressively pursue this to the end, regardless. We can't tolerate major illegality at the heart of the political process, even if we end up liking some of the results. I discuss local issues at 8:50 a.m. Friday on WAMU (88.5 FM). I'm also going on holiday. My column will return Jan. 3 with the 2013 predictions quiz. For previous columns, go to washingtonpost.com/ mccartney.