Robert M. “Bobby” Joost, a well-known mob associate from Providence, will not be getting out of prison any time soon.

The 1st Circuit Court of Appeals, in Boston, upheld convictions against Joost in District Court, Providence, for conspiring to obstruct commerce by robbery of an armored car and of being a felon in possession of a firearm.

The verdicts were reached in the mid-’90s and he was sentenced to 26 years in prison.

In April 1995, Joost, of 40 What Cheer Ave., in the Silver Lake section of Providence, was convicted of conspiring to rob a Meehan armored car carrying millions of dollars in gold in northern Rhode Island. In a separate trial in federal court, he was convicted on the gun charge.

What made the case even more compelling was that two of Joost’s accomplices were undercover state police detectives: Steven G. O’Donnell, now a state police major, and Detective Joseph S. Del Prete. At the time, both detectives were assigned to the state police organized crime/intelligence unit.

During the course of their relationship, investigators said, Joost recruited the undercover detectives to rob the Woonsocket-based armored car company. Joost, an ex-convict with financial problems, also was accused of lending the detectives a .25 caliber pistol to rob a nightclub on Cape Cod.

Joost, a jailhouse lawyer who defended himself at trial, appealed his convictions. At one point, the conspiracy conviction was affirmed, while the gun conviction was vacated and a second trial was ordered. A jury again found Joost guilty on the gun charge.

Joost continued to fight the verdicts. From his prison cell in Otisville, N.Y., he obtained investigative documents from the Justice Department through a Freedom of Information Act (FOIA) request.

Joost used the documents to bolster his argument during his earlier trial that the undercover state troopers had entrapped him.

The appeals court disagreed.

“It is clear from this material, as it was from the court testimony, that the agents were seeking to direct Joost’s energies to a high-penalty armored-car robbery or firearms crime rather than the other serious ventures which did not involve firearms,” the court wrote. “But there is nothing in the details provided by the FOIA material that alters the main thrust of what the jury learned at the trial.”

Joost, now 62, has spent more than a third of his life in prison.

In the early 70s, he was sent to federal prison for 14½ years for conspiring to kill a witness who was scheduled to testify against him for stealing 32 M16 military rifles from a National Guard armory in Westerly.

The witness, Daniel LaPolla, was blown apart when a dynamite booby trap exploded in his home in Sterling, Conn.

Joost is scheduled to be released from prison in March 2017.

bmalinow@projo.com