Friends, family and colleagues crowded the jury reception room at the historic courthouse on Friday evening to welcome Napa County’s 22nd superior court judge to the bench.

Mark Boessenecker, 48, the former Napa County Chief Deputy District Attorney, had his official swearing in months earlier, on Sept. 21, without much fanfare.

On Friday evening at his ceremonial swearing in, he took the oath of office in front of a roomful of Napa County elected officials, court staff, law enforcement officers and others who have worked and known Boessenecker since he joined the Napa County District Attorney’s Office four years ago.

“I’m a little nervous. But it’s really wonderful to be here with my family, friends and colleagues,” Boessenecker said before the festivities got under way.

“I’ve been on the bench for six weeks. It’s been a learning experience. I love every minute of it, but I have to say I miss the people I worked with at DA’s office. You can’t work with such a great bunch of people for that many years and not miss them,” Boessenecker said. “But I really look forward to the new challenge. It’s what I want to do.”

Boessenecker, who was appointed by Gov. Arnold Schwarzenegger, will complete Napa County Superior Court Judge Ronald Young’s term, which expires in 2010. Young was force to leave the bench because of a medical disability, and officially retired in May.

In 2010, Boessenecker will stand for election by Napa County voters.

At Friday’s swearing in, the other four current superior court judges, two commissioners and other county and city officials took the podium to praise and share their humor about Boessenecker, who was sitting in the front row next to his wife, sons, mother, siblings and other family members.

“We are like a big family, so I know Mark will enjoy working with us since he comes from a family of six siblings,” said Napa County Superior Court Presiding Judge Francisca Tisher, who went on to praise Boessenecker’s compassion, which he showed the victim’s and their families when he was a prosecutor.

Judge Ray Guadagni presented Boessenecker with a baseball jersey and cap, with the word “rookie” on the back.

Other speakers highlighted Boessenecker’s professionalism, eloquence and fairness.

The newest court commissioner, Monique Langhorne-Johnson, was a Napa County deputy district attorney before she was appointed to the bench.

Before her appointment, Boessenecker was her boss. “He was a great supervisor and always treated everyone with great respect,” she said. “And it was a good thing I got along with him so well, since he is my boss again.”

Boessenecker joined the Napa County District Attorney’s Office in 2004, after serving as chief deputy prosecutor with the San Mateo County District Attorney’s Office.

During his tenure in Napa County, Boessenecker has prosecuted several homicide cases, including the double stabbings of two young Napa women in their home in 2004. The case drew national media attention. Napa resident Eric Copple pleaded guilty to stabbing to death Adriane Insogna and Leslie Mazzara, both 26. He was sentenced to life in prison without the possibility of parole.

Boessenecker has racked up many accomplishments in his years of public service.

“I am proud of the (40 to 50) homicides cases I have prosecuted and been successful. I also have found it very rewarding to be a mentor to the young attorneys,” Boessenecker said before the ceremony.

Boessenecker, a Democrat, was appointed by a Republican governor. In fact, Gov. Schwarzenneger has appointed to the Napa bench two Democrats — Boessenecker and Diane Price — and one Republican, former commissioner Rodney Stone.

Choosing a law career wasn’t that difficult for Boessenecker. It runs in the family. His father is an attorney, as are his sister and brother.

Boessenecker grew up in Mill Valley, graduating from Marin Catholic High School in 1977. He attended UC Santa Barbara, earning a bachelor’s degree in economics in 1981. He then taught school at a group home for emotionally disturbed youngsters from 1981 to 1983 in Santa Barbara.

It was around this time the family’s law history nudged him, and Boessenecker enrolled at Hastings College of Law, graduating and passing the bar in 1986.

Fresh out of law school, Boessenecker joined the San Mateo County District Attorney’s Office, where he served as a prosecutor until accepting the chief deputy district attorney position with Napa County.

Boessenecker and his wife, Janet, have two sons, Brian, 15, and Eric, 12.