Chadbourne & Parke welcomed high-profile defense attorney Abbe D. Lowell back into the fold last week and days later Lowell was back in the news defending another of the big-name Washington clients that he has become known for — former senator John Ensign.

Lowell left Chadbourne in 2007 after leading the firm’s white-collar defense and special litigation and investigations group for four years. He went on to hold the same position at the much larger McDermott Will & Emery, before deciding to return to his Chadbourne post last week.

New York-based Chadbourne announced Lowell’s return May 9, with the firm’s managing partner, Andrew A. Giaccia, issuing a statement calling Lowell a friend.

“Sometimes law firms are hesitant to ‘embrace’ a partner who had left,” Giaccia said. “In Abbe’s case, there was real enthusiasm and not a moment of hesi­ta­tion when this opportunity arose.”

Ensign, the former Republican senator from Nevada who acknowledged having an affair with a political aide, hired Lowell to defend against a possible investigation by the Justice Department and Federal Election Commission. The Senate Ethics Committee reported last week that it had “substantial and credible evidence” that Ensign had broken federal laws in attempting to conceal the affair.

The former senator is the latest in a long line of famous Washington defense clients for Lowell, among them lobbyist Jack Abramoff and former Nevada governor Jim Gibbons.

Prosecutor joins Mintz Levin

Veteran Justice Department prosecutor Paul E. Pelletier has joined the District office of law firm Mintz Levin Cohn Ferris Glovsky and Popeo. The Boston-based firm has brought him on to expand its white-collar defense practice.

“Paul comes to Mintz Levin with a wealth of experience handling high-profile, high-stakes investigations and trials across a broad range of industries including securities, commodities, banking and health care,” Robert I. Bodian, managing member of Mintz Levin, said in a statement.

Pelletier is widely credited with building the Justice Department’s Criminal Fraud Section while serving as principal deputy chief of litigation for nine years. He recruited and trained dozens of attorneys to try insider trading as well as financial and health care fraud.

The chief prosecutor also led the fraud enforcement efforts in the agency’s Criminal Division during the financial meltdown of the late 1990s and the recent banking crisis. Pelletier most notably worked on several high-profile fraud cases including investigations of American International Group, Enron and British Petroleum.