This is one of the tools the American Mafia used in the 1930's and '40's.

This happened while he had two cops guarding him in his hotel room, another several in the halls and outside:

Abe "Kid Twist" Reles was a triggerman for Murder Inc., the infamous squad of Mob hitmen, active from 1929 to about 1941. Reles killed at least 11 people at the request of his superiors, but his real count may have been closer to 30. He ended his criminal career in 1940 as a government informant and by 1941, he had testified in three Murder Inc. cases and sent several of his former colleagues to the electric chair.

Reles was scheduled to testify against alleged Murder Inc. boss, Albert Anastasia on November 12, 1941, but in the early morning before he was to appear in court, Reles jumped, fell or was forced out of a sixth-floor window of the Half Moon Hotel in Brooklyn, New York, where he was being held in protective custody by officers reporting to the DA's office. His death was never solved. The information he provided helped solve at least 85 gangland murders, including the 1935 killing of Mob boss Dutch Schultz.