(CNN) -- Calling him "one of the most violent and despicable criminals in Boston history," prosecutors argued Thursday that convicted mob boss Whitey Bulger should never set foot on the streets of that city -- or any city -- again.
"Having now been convicted of 31 felonies, including ... counts involving multiple murders, Bulger richly deserves to spend the rest of his life in jail," U.S. Attorney Carmen Ortiz said in a sentencing memorandum filed Thursday.
Bulger embarked on what prosecutors called "a decades-long crime spree" and then went into hiding. He was finally found, after 16 years on the run, with his girlfriend, Catherine Greig, in Santa Monica, California, in 2011.
A two-month trial culminated in his conviction last August on various counts such as racketeering, extortion, and money laundering. The federal jury linked him to 11 murders; the government had alleged he had a role in 19 such killings between 1973 and 1985; the jury said it had failed to prove his involvement in seven of those and had "no finding" in the other.
The 84-year-old's sentencing hearing is set to begin Wednesday.
The prosecutor noted that convictions on many of the counts mandate a life sentence.
"There are no mitigating factors, and defendant Bulger has no redeeming qualities, which would justify any sentence below the one called for by the U.S. Sentencing Guidelines and the applicable case law and statutes," Ortiz wrote.
The prosecutor also asked the court to take steps "to prevent any money -- where earned from his crimes or obtained in the future -- from finding its way into Bulger's pocket." She also asked that restitution be paid to the murder victims.
Paperwork filed earlier in federal court indicated Bulger generated well over $25 million in racketeering proceeds between 1972 and around 2000, five years after he went on the lam after being tipped off by his rogue FBI informant to a pending indictment.
The sentencing memorandum also summarized what the government describes as "Bulger's horrific crimes and sadistic behavior" as further proof "that he deserves no mercy at the time of sentencing."
"Presiding over a massive criminal enterprise, Bulger extorted dozens of individuals, flooded South Boston with cocaine, shot innocent people, strangled women, murdered his competitors, corrupted FBI agents, and then ran away and hid for 16 years," the prosecutor said.
Their judgment didn't improve during this summer's trial, with Ortiz accusing Bulger of playing "an elaborate game of 'Let's Pretend'" by denying being an FBI informant while at the same time insisting the federal government "had given him full immunity."
CNN's Ross Levitt contributed to this report.