The retired FBI supervisor who led the federal probe into the Lufthansa heist told The Post on Thursday that he “had a feeling” the case might be too threadbare to convict accused mobster Vincent Asaro.

“My gut feeling was that they didn’t have enough evidence,” said Stephen Carbone, 74, who spent countless hours probing the infamous Dec. 11, 1978, ripoff.

“When I realized that the only witness was the cousin, I didn’t feel that would be enough to convict,” he said.

Carbone, who is long retired from the bureau, said he monitored the trial’s developments by reading daily newspaper accounts and spoke with federal officials before the trial started.

He insisted that he had “no inside knowledge” on whether Asaro was guilty of plotting the heist with Jimmy “The Gent” Burke, as the government charged.

Carbone recalled Asaro’s name emerging during the course of the lengthy and far-flung investigation but only as one of many mob soldiers who were active back then.

“He was a soldier,” Carbone said of Asaro. “He was significant as any other soldier in the group [the Bonanno crime family]. We did not target him.”

The name of Gaspare Valenti — Asaro’s cousin who wore a wire for years and whose cooperation with authorities led to Asaro’s arrest in January 2014 — did not surface in the immediate aftermath of the Lufthansa heist, Carbone noted.

Carbone said that while he did not attend the trial himself, he spoke to a number of people who did — he declined to say whether they were law enforcement officials — and they too “didn’t feel there was enough evidence” to convict Asaro.

“Here’s the deal: From what I remember, I know there is a general policy that when you go to trial [in federal court], you feel confident 90 percent of the time,” he said.

“I’m sure they put a lot of work into it and feel very disappointed.”