When prosecutor Paul Cummins retires this summer, attorneys say, the San Francisco district attorney’s office will lose a longtime mentor and the criminal defense bar a trusted liaison.

“Paul’s been the go-to guy at the district attorney’s office and the Hall of Justice for as long as I can remember,” said criminal defense lawyer Douglas Rappaport.

The 33-year veteran of the office said Wednesday that he hasn’t settled on a date of departure yet because he’s waiting to see whether the city will come through with an increase in retirement benefits for prosecutors and deputy public defenders in the next few months.

“I really believe that one way or the other, it’s going to be decided after July 1,” he said. “As soon as it goes through, I would go.”

Cummins notified the office’s chief assistant DA, Russell Giuntini, of his intended departure last week, he said Wednesday.

Both Giuntini and District Attorney Kamala Harris declined through a spokeswoman to comment, citing issues of employee confidentiality.

Cummins wouldn’t say whether his retirement was accelerated by a job change about a week prior when Harris reassigned Cummins from the head of the office’s entire criminal division. He’s now head of the two-attorney career criminal unit, which prosecutes defendants charged in Three Strikes cases and crime sprees.

“It’s not been a company secret that I’ve been talking about retirement openly for the last year,” said Cummins, 58, adding simply, “Now is a good time.”

His primary focus at the outset will be spending more time with his elderly father, his wife and his three young children. He says he still expects to work again, but hasn’t given much thought to where yet — saying only that he won’t be a defense attorney and probably won’t be a prosecutor.

“My biggest thing is being with my father and my family,” he said.

In the DA’s office and around the Hall of Justice, Cummins has earned a reputation as a well-liked teacher and a straight shooter, respected by prosecutors and defense attorneys alike for his ability to weigh the worth of a case, attorneys said.

“Paul Cummins has been a giant in the landscape of the DA’s office,” said Assistant DA Robert Gordon. “He’s been a fantastic mentor to a lot of attorneys, including myself, and I’ve been here 25 years.”

“He’s always been one of the people that you go to when you have a complicated issue,” said Assistant DA Pamela Hansen, a gang prosecutor who’s been in the office nearly 19 years. “There’s probably one other person in the office who not only does trials, but who is a supervisor who many people go to to ask questions,” she said, naming prosecutor George Butterworth.

Cummins has been a valuable liaison between the DA’s office and the defense bar, said Martin Sabelli, the public defender’s director of training, who has worked opposite Cummins on the current case against a man accused of killing San Francisco police officer Isaac Espinoza.

“I think extremely highly of Paul,” Sabelli said. “He’s an open line of communication because he’s trusted and respected. And the loss of a person of that nature will just make it a little bit harder to mend fences occasionally and to resolve issues.”

Cummins has long been the “unofficial liaison” between the defense bar and the DA’s office, said Rappaport, who praised the prosecutor as professional, open-minded and exceedingly fair. At the Hall of Justice, “We’re a big, dysfunctional, extended family,” he said. “And Paul has always been the favorite uncle.”

He and others credit Cummins for settling a number of cases that would otherwise have gone to trial. He was so effective, in part, because everyone at the Hall has known and trusted him for so long, Rappaport added.

“Not to say that Russ isn’t trustworthy or Kamala isn’t trustworthy,” he said, “but [defense attorneys] have less experience with them.”

Under the previous district attorney, Terence Hallinan, Cummins’ departure would have left “a huge vacuum” for the police department, but the lines of communication have opened up under Harris, said Deputy Chief Greg Suhr.

Under Hallinan, Cummins “really was our conduit to the DA’s office,” someone police would turn to, Suhr said, when they felt a decision was unreasonable or arbitrary. “I think now we have many conduits,” he said.

“I wish him well,” Suhr added. “Hopefully the mentoring that Paul did is going to leave a few Paul Cumminses behind . . . and he can enjoy the fruits of his labor.”

A big question as Cummins retires is whether the pension increase prosecutors and deputy public defenders are hoping for will come soon enough to benefit him. He’d get 66 percent of his current $165,000 salary under the current pension plan, versus 90 percent under the proposed increase, he said.

Voters last year gave the city the green light to increase pensions for local prosecutors and deputy public defenders, to bring them more in line with retirement benefits for probation officers and district attorney investigators.

But that change won’t happen without further action by the Board of Supervisors and mayor.

That could happen as soon as this summer, when city officials are supposed to vote on the next contract with the Municipal Attorney’s Association during their annual budget season.

The retirement increase is on the table now as the union and city negotiate, said the city’s chief negotiator in the talks, Arthur Hartinger, a partner with Meyers, Nave, Riback, Silver & Wilson.

But that doesn’t mean the pension increase will necessarily materialize.

The measure the voters passed last year only allows the increase if it doesn’t cost the city any more money, so the union would have to make concessions in other areas.