"Cadillac Frank" Salemme is on trial for the murder of Steven DiSarro, and it is his own fault.

First of all, according to the government, the Boston mafia boss ordered the killing of DiSarro and the disposal of his body by his underlings.

But he also had a chance to avoid being prosecuted for the murder when he made an immunity agreement with the federal government. All he had to do was admit to the crime, and it would have been included in his deal and essential forgiven.

So why didn't Frank Salemme admit to the crime and save himself from the trial he is involved in now? Who was Salemme protecting, and why?

According to the government, Frank Salemme Jr. and Paul Weadick, "Cadillac Frank's" co-defendant today, strangled DiSarro because he was a federal informant. After the murder, Frank Sr. coordinated with Robert "The Cigar" DeLuca and his brother Joe DeLuca to dispose of the body in Rhode Island. The body was buried behind a warehouse for decades, and would have stayed there, until a low-level mobster gave up the location and Bobby DeLuca to save himself from a drug rap.

Bobby DeLuca by this time was also in the witness protection program, and had an immunity agreement with the federal government. Like Salemme, he decided against confessing to the DiSarro murder and being absolved of it by the legal system. It seems obvious that DeLuca didn't want his brother charged in the case, so he didn't tell the government about the murder. He also knew that Salemme had kept quiet about the murder and protected all of the mobsters involved in the slaying.

When the body was discovered in 2016, "The Cigar" burned the "Cadillac" to save himself and his brother. He stayed committed to his brother and kept him out of legal jeopardy.

But what was it that kept Frank Salemme quiet?

Salemme's son was dead of natural causes after a long illness, so that wasn't the motivation for his silence. The only people he was keeping safe in the DiSarro case were the DeLuca brothers and Weadick.

Did he protect them because they were still keeping his criminal affairs in order on the street while he was in the witness protection program? Bobby DeLuca was on the street and active in the Patriarca family for many years after Salemme had gone into the program. According to the government, Weadick was active in organized crime up to his arrest for the DiSarro killing. So perhaps Salemme still had rackets and needed soldiers.

Or maybe it was just loyalty to his former soldiers that kept Salemme from giving them up to the government. A loyalty that DeLuca no longer felt for "Cadillac Frank" when the government came to him with the body he had helped to hide in 1994.

Chris McCarthy is the host of The Chris McCarthy Show on 1420 WBSM New Bedford. He can be heard weekdays from 10 a.m. to noon. Contact him at chris.mccarthy@townsquaremedia.com and follow him on Twitter @Chris_topher_Mc. The opinions expressed in this commentary are solely those of the author.