Carroll A. Weimer Jr., one of two lawyers confirmed to the county bench this month, was once asked to defend a man who carried out one of Northern Virginia’s most vicious crimes.

In the late 1990s, Paul W. Powell was convicted of the brutal stabbing murder of 16-year-old Stacie Reed in Manassas. Powell had confessed to the crime and was behind bars when his sentence was overturned by an appeals court in 2001.

Then the case got stranger.

Thinking he had escaped execution after the state Supreme Court’s actions, Powell sent a rambling, profanity-laced letter to Prince William County Commonwealth’s Attorney Paul B. Ebert in 2001, ridiculing the prosecutor for failing to make the death sentence stick, The Washington Post reported at the time.

Prompted by new information in the letter, Ebert’s office filed new charges against Powell. Weimer took over the case, defending Powell. It was Weimer’s only capital murder trial in a sprawling legal career. Despite his efforts, Powell was later sentenced to death and was executed in 2010.

As Weimer rises to the Prince William County Circuit Court, he has behind him a diverse career, informed by cases as dramatic as Powell’s and by day-to-day criminal defense work. As a former police officer, defense attorney and Republican Party challenger, Weimer said that he hopes his life experience will help him decide on complex issues of law that have serious consequences.

He ran in a Republican primary for a Board of County Supervisors slot in 1987 and again against Del. Jackson H. Miller (R-Manassas) for a House of Delegates slot in the early 2000s, both of which he lost. Weimer said he has long wanted to be involved in government service, prompting brief forays into local politics.

Weimer, a 57-year-old Prince William native, worked as a police officer in Manassas and Alexandria before entering law practice. Serving in different capacities in the justice system — both going after criminals and defending them — has informed his sense of justice, he said.

Weimer said he has learned that the justice system works “most of the time. But it works best when there are good lawyers on both sides, and a judge who will listen,” he said. Weimer said the best metric for his new role was from the judge he replaces, William D. Hamblen, who retired last year: You want to be able to go home and say you did the right thing for the right reason, he said Hamblen told him.

In Powell’s case, Weimer argued that Powell shouldn’t be put to death, because the state should not have been able to try the same crime twice, known as double jeopardy. “I thought we had a shot,” Weimer said. “I was wrong.”

One of his most powerful memories is meeting Powell’s mother. She told Weimer about her son’s troubled upbringing.

“For me, it made Paul Powell human,” Weimer said. “I never could understand what he did, but I could understand why he was difficult.”

Longtime municipal and criminal defense attorney Lisa M. Baird was also confirmed this month to be a judge on the juvenile and domestic relations court in Prince William. Baird, a Manassas lawyer in private practice, has prosecuted misdemeanors for Manassas and the towns of Haymarket and Dumfries. She replaces Judge Paul F. Gluchowski, who retired.

Over the past three years, Baird, 39, served as a substitute judge. “I had an idea I wanted to run for this — I think subbing solidified that,” Baird said. “I enjoyed serving the citizens of Prince William County.”

She said it has been especially revealing dealing with Department of Social Services cases on behalf of municipalities, which are similar to cases she’ll see in her new role. “You get a true understanding that this is their personal life they’re dealing with,” she said.

Candidates for the county’s courts are submitted by the local bar association and confirmed by the General Assembly. Both judges begin their new terms next month.