When federal authorities began to investigate allegations of corruption involving prominent D.C. politicians and their campaigns last year, U.S. Attorney Ronald C. Machen Jr. took a keen interest in the probes.

Machen, the District’s top prosecutor, prodded his staff to work through weekends, demanded regular progress reports, set rigid deadlines and helped shape investigative tactics.

Although former and current prosecutors have described early friction in law enforcement circles over whether the probes would yield federal prosecutions, they said the effort paid off with recent high-profile guilty pleas and resignations.

“I’m not sure that without Ron’s leadership that the office would have gotten where it is on these cases,” said Thomas Hibarger, who resigned last month as Machen’s chief prosecutor in federal court to join a digital risk management company. “Ron really pushed us hard, rode us hard. . . . Ron is a force of nature.”

As if investigating D.C. public corruption wasn’t enough, Machen and his prosecutors were handed another difficult task June 8: spearheading a probe of leaks of classified material to reporters. That assignment came the same day that former D.C. Council chairman Kwame R. Brown (D) pleaded guilty to federal bank fraud charges; Brown resigned just days earlier when he was charged in federal court by prosecutors who, with FBI agents, began by investigating discrepancies in his 2008 council campaign.

Brown’s conviction followed guilty pleas in which two top staff members on Democrat Vincent C. Gray’s successful 2010 mayoral campaign admitted to participating in an illegal scheme to improve their boss’s election chances. Federal prosecutors and FBI agents are investigating a prominent D.C. contractor — they seized millions of pages of records in raids — and his ties to city leaders.

High-profile job

That such cases landed in Machen’s lap is not unusual. As the District’s U.S. attorney, Machen has one of the most sought-after jobs in federal law enforcement.

The former partner at WilmerHale has labored to leave his own stamp on the country’s largest U.S. attorney’s office, which has about 300 lawyers handling matters in federal court and D.C. Superior Court and a budget that purportedly exceeds $70 million. (Although other U.S. attorneys have publicized their budgets, Machen has not.)

Machen, a tall and slightly bulky former college football player known for working so intensely that he has not yet removed Christmas decorations from his office, has left his mark in several ways — in public corruption convictions and by pushing prosecutors to get out into the community.

But his hard-charging style has alienated some, and he is battling an unusual number of departures by key supervisors and courtroom prosecutors, particularly those handling violent crimes.

Attention to detail

Unlike most of his predecessors, Machen relishes the minutiae of criminal prosecutions, including the trials of retired baseball star Roger Clemens — acquitted this week of lying to Congress about alleged steroid use — and of five men recently convicted of participating in shootings that claimed five lives in 2010.