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Another Montgomery County prosecutor on Bill Cosby's criminal case has gone into private practice.

Assistant District Attorney M. Stewart Ryan will be leaving the Montgomery County District Attorney's Office on Friday, to join Laffey, Bucci & Kent, a Philadelphia plaintiffs firm, as an associate. The DA's Office announced his departure Wednesday.

Ryan will stay on as a special prosecutor through Cosby's sentencing, set to take place Sept. 24 and 25 in the Montgomery County Court of Common Pleas.

M. Stewart Ryan.

Ryan's arrangement is similar to that of Kristen Gibbons Feden, a fellow Montgomery County prosecutor turned private-practice lawyer. Feden joined Stradley Ronon Stevens & Young in August, but took leave from the firm to help prosecute Cosby at his retrial, which took place in April.

Ryan and Feden shared closing arguments in the case, which resulted in Cosby being found guilty on all counts of aggravated indecent assault, based on Andrea Constand's allegations that he sexually assaulted her in 2004.

“I'm grateful the district attorney gave me the chance to see that case through to conclusion,” Ryan said. “It's an important case. One of I think many important cases I have worked on” as a prosecutor.

Ryan, who joined the District Attorney's Office in 2012, was also part of the team that prosecuted former Pennsylvania Attorney General Kathleen Kane. Her case ended in a guilty verdict in 2016, when a jury found that she had leaked grand jury secrets and lied about it under oath. She was sentenced to jail time but is currently out on bail while her appeal is pending.

“We are disappointed to lose such a promising young attorney, and I will miss him personally and professionally,” District Attorney Kevin Steele said in a statement. “However, I am pleased that Stew, with the support of the law firm of Laffey, Bucci & Kent, wanted to see the Cosby prosecution through to its conclusion.”

Steele said Ryan had a “methodical but compassionate approach to presenting sexual assault cases.”

Ryan said he has always been interested in joining a plaintiffs firm so he could continue to litigate in court.

“With this firm in particular, while they handle everything you can imagine in terms of plaintiffs work, they do have a very strong practice in crime victims litigation,” he said, adding that is an area he hopes to pursue.

Ryan said he got to know Laffey Bucci name partner Brian Kent several years ago, through both of them being alumni of La Salle College High School. When Cosby's trial concluded, Ryan said, they reconnected over the possibility of Ryan joining the firm and formalized the move.

“Stewart brings an unrivaled work ethic, passion and courtroom ability that was further developed under the tutelage of District Attorney Kevin Steele and exemplified in Stewart's successful prosecution of Bill Cosby,” Kent said in a statement Wednesday. “We have no doubt that the victims and families that Laffey, Bucci & Kent represent will benefit tremendously having Stewart as their tireless advocate.”