BOSTON (AP) — Three former officials in the state Probation Department were to be sentenced on charges they rigged the agency's hiring process to favor politically-connected candidates.

Federal prosecutors have recommended a nearly six-year prison sentence for former Probation Commissioner John O'Brien and five-year sentences for his former deputies, Elizabeth Tavares and William Burke.

But O'Brien's lawyers, in their sentencing memorandum, argued that imposing nearly the maximum allowable sentence under law, as prosecutors recommend, would be a "grave injustice." They've asked for leniency, arguing that O'Brien "has been punished enough."

U.S. District Court Judge William Young was set to hand down his sentence Thursday afternoon. Both O'Brien and Tavares were convicted by a jury of racketeering and mail fraud this summer, while Burke was found guilty of the lower charge of racketeering conspiracy.

The two-month trial shined a light on patronage culture in state government.

"Although society has attempted to rid itself of crony politics, the defendants apparently never received that message," prosecutors from the U.S. Attorney's office for Massachusetts wrote in their sentencing memorandum.

Prosecutors alleged the defendants, led by O'Brien, created a "sham" process designed to circumvent the agency's merit-based hiring policies. The defendants made sure coveted probation officer jobs went to candidates backed by legislators or other officials, often at the expense of more qualified applicants.

No current or past lawmakers were ever charged, and House Speaker Robert DeLeo, who was among the prominent politicians named during the course of the trial, has vehemently denied any wrongdoing. Boston Mayor Martin Walsh, a former state lawmaker, is among the prominent figures that have publicly defended O'Brien since his conviction.