HARTFORD — Robert Gentile is either a dangerous mobster who should remain locked up for illegally possessing weapons and selling prescription drugs or an ailing old man with no proven mob ties who poses no danger to society and should be released from detention, according to federal court documents.
The dueling depictions come from legal briefs filed by the prosecution and defense ahead of Gentile’s sentencing scheduled for Thursday in Hartford.
Prosecutors are seeking a prison sentence of about four to 4½ years, while Gentile’s lawyer said he should be sentenced to time already served and be released on probation or home confinement.
The case made national news last year when prosecutors said the FBI believed that Gentile had information on the single largest property heist in US history, the still-unsolved theft of art worth an estimated half-billion dollars from the Isabella Stewart Gardner Museum in Boston in 1990.
Gentile, 76, has denied knowing anything about the art heist, no one has been charged in the theft, and there is no mention of it in the recent court filings in Gentile’s case.
In March 1990, two men posing as police officers stole 13 pieces of art including paintings by Rembrandt, Manet, Degas, and Vermeer. FBI officials said earlier this year that they believe they know who stole the paintings, but still do not know where the artworks are.
Gentile has been detained since his arrest in February of last year and pleaded guilty in November to the weapons and prescription drug charges.
Federal agents said they found an arsenal of weapons at Gentile’s Manchester home including several handguns, a shotgun, five silencers, hundreds of rounds of ammunition, and homemade dynamite.
Authorities also searched the property with ground-penetrating radar in what Gentile’s lawyer called a veiled attempt to find the stolen artworks, but did not find the paintings.
Gentile and a codefendant, Andrew Parente, were also charged with selling dozens of prescription drug pills including Dilaudid, Percoset, and OxyContin. Parente has pleaded guilty and is set to be sentenced later this month.
Assistant US Attorney John Durham wrote in his sentencing memo that Gentile has been identified by several people as a member of a Philadelphia crime family who has been involved in criminal activity for virtually his entire adult life.
‘‘Common sense dictates that one conclude the defendant is a dangerous individual,’’ Durham wrote in a brief filed Saturday. ‘‘What even remotely lawful purpose was there for the defendant to be in possession of: multiple handguns, multiple silencers, a loaded pistol-grip shotgun hanging from a door frame inside his residence, a bulletproof vest, police scanner, handcuffs, Tasers, switch blade knives, and explosive devices?’’
Durham said a captain in the Philadelphia La Cosa Nostra, Robert Luisi, told authorities that Gentile had committed robberies and possibly other violent crimes and once planned to rob an armored car carrying money from a Connecticut casino. Luisi also said that Gentile once lived with him in Waltham and that Gentile was his bodyguard.
In his brief Friday, Gentile’s lawyer, A. Ryan McGuigan, called Luisi’s allegations ‘‘hearsay’’ and said the government has never proven any link between Gentile and organized crime.
He also said Gentile’s criminal record, before the current case, includes only old convictions for nonviolent crimes.
McGuigan said Gentile is a family man and retired bricklayer, concrete mason, and automobile dealership owner. He said Gentile’s last conviction was for larceny in 1996 involving improper distribution of proceeds from his father’s estate.
Gentile’s other convictions were in 1956, 1962, and 1963 for receiving stolen goods, carrying a deadly weapon in a motor vehicle, and possession of illegal firearms, respectively, McGuigan said.