Even though law enforcement would never recover the money from the robbery, their pursuit of the matter was relentless. According to Assistant United States Attorney Edward A. McDonald, “there was never any mystery about who robbed Lufthansa.” DeSimone, Sepe, Frank Burke, and Anthony Rodriquez were the four people they had focused on since their names were given up by snitches within hours of the robbery (although no substantial proof about Rodriquez’s involvement ever materialized). A member of the Colombo Family, who was an informant, told his FBI handler that Burke was the man behind the robbery. In addition mug shots were shown to beating victim Kerry Whalen and the others who saw two of the robbers without their masks. Whalen identified Angelo Sepe as the man who assaulted him. Tommy DeSimone’s picture was selected by the employees as the other mask-less robber.

McDonald requested court approval to install homing devices and electronic bugs in automobiles belonging to Burke, DeSimone and Sepe. In Wiseguy Pileggi explains that the surveillance went on for weeks and turned into a “game of nerves.”

Pileggi wrote that the crew became “so adept at slipping tails,” they would even disappear for days at a time, even leaving the state. McDonald could have revoked their paroles because of this and for consorting with known felons – each other – but that wasn’t going to help find the Lufthansa money.

On February 7, 1979, 10 people were subpoenaed to appear before a federal grand jury in Brooklyn. Among them were alleged members of the Lucchese Family. Just days after the testimony, information was released to the press that Edwards was believed to have been murdered by the now missing Tommy DeSimone and that both were connected with the robbery.

On February 17, the FBI made its first arrest in the robbery, picking up Robert’s Lounge crewmember Angelo Sepe.  The arrest came after a confidential informant for the FBI reported seeing Sepe armed around the time of the robbery. Bail was set at $1 million for Sepe, who police described as an associate of Paul Vario.

During the investigation into the disappearance of Tommy DeSimone, it was discovered he had been living in a halfway house in Manhattan on the day of the robbery.  It wouldn’t take the authorities long to realize who else was living at the same location – James Burke.  On February 22, the New York Times reported that Lieutenant Thomas Ahearn of the 113th Precinct stated that, “James Burke, a former convict associated with the Paul Vario organized crime ‘family,’ was another prime suspect in the Lufthansa case.”

The newspaper reported that Anthony Rodriquez, a friend of Angelo Sepe, was also considered a suspect.  In January 1978, Rodriquez had been arrested with Sepe in Angelo’s Long Island home where the FBI recovered drugs and guns. Both men went free when it was discovered that the search warrants were not properly executed.  Although his name surfaced several times during the investigation, Rodriquez was never considered a serious suspect. When police arrested Sepe, they searched his home in hope of finding some of the Lufthansa loot.  Instead, all they found was James Burke. 

On March 23, charges of participating in the Lufthansa robbery were dropped against Angelo Sepe.  However, he was still being held for violating the terms of his probation for consorting with another felon – James Burke.  Oddly enough, on April 12, Burke would be arrested for violating the terms of his probation for consorting with a known felon – Angelo Sepe.

In addition to chasing the Robert’s Lounge crew around town, agents grilled Peter Gruenwald and Louis Werner relentlessly. Neither man would admit having any role in the robbery despite the fact that Werner had paid cash for a new customized van and Gruenwald had paid off his debts. Both men claimed that their recent cash windfall was due to a recent streak of good luck in gambling.

In early February 1979, Gruenwald was served with a summons to appear before the federal grand jury that was investigating the robbery. Gruenwald had scheduled a vacation, which had him leaving for the Far East on February 19 to spend some time with his ex-wife. Gruenwald apparently did not know that because of the summons, he was not permitted to leave the country. The FBI was notified immediately of his travel plans and Gruenwald was arrested as a material witness and held in jail.

Gruenwald was taken to McDonald’s office where the prosecutor expounded the merits of cooperation. When he found his speech falling on deaf ears, McDonald had Gruenwald sent to the Nassau County Jail to spend the night. A few hours with the rough jail population was all it took to loosen the Lufthansa employee’s lips.

The next day Gruenwald told a fascinated audience of law enforcement personnel everything he knew, including his and Werner’s role in the 1976 robbery. With this information, agents were off to arrest Frank Menna and William Fischetti. When Menna encountered two FBI agents at his door he announced, “I want a lawyer. I want immunity.” Fischetti, on the other hand, was only concerned that his wife not find out about his affair with Beverly Werner.

The last two pieces McDonald needed before arresting Werner were information from his wife, Beverly, and his girlfriend, Janet Barbieri. Werner had boasted to both women his role in the robbery. When questioned, the women confirmed his claims. Although his wife’s testimony could not be used against Werner, McDonald felt comfortable after Barbieri’s admissions to the grand jury.

On February 20, Louis Werner was taken into custody as he was getting into his brand new 1979 customized sports van outside a Long Island bowling alley.