The burglary had all the trappings of a Hollywood heist, and the theft unfolded in London’s jewelry district during Easter weekend in 2015. The group of men in their 60s and 70s, disguised as workmen, slid down the elevator shaft at Hatton Garden and used a heavy-duty diamond-tipped drill to break through the vault walls.

The thieves ransacked 73 safe deposit boxes and stuffed the loot into plastic garbage cans before making their getaway. Officers later found the book “Forensics for Dummies” at one suspect’s home. They continued to use their cellphones after the burglary, helping detectives to trace them.

Prosecutors said that the ringleaders — Daniel Jones, 61; Terrence Perkins, 67; John Collins, 75; and Brian Reader; 77 — had received an estimated £13.7 million from the burglary, but only £4.3 million has been recovered.

In a confiscation hearing this year, prosecutors said that the gang members must pay back more than £6 million each based on their “available assets” or face an additional seven years in jail.

“A number of these defendants are not only of a certain age, but have in some cases serious health problems,” Judge Christopher Kinch said during the hearing. “But as a matter of principle and policy, it is very difficult to endorse any approach that there is particular treatment for someone who chooses to go out and commit offenses at the advanced stage of their lives that some of these defendants were.”