Whitman's office continued to investigate Becker. On July 29, 1912, Becker was arrested at the precinct's closing hour by special detectives from the District Attorney's Office. He was tried and convicted of first degree murder that fall in a trial presided by
John Goff, who was "intensely biased against Becker" and whose charge to the jury was slanted toward conviction. The verdict was overturned on appeal on the grounds that Goff had been biased and that there was no independent corroborating witness to testify to the events since all of them had been involved in the crimes. and John Brennan (executed on December 2, 1926). Becker continued to profess his innocence. The day before his execution, Becker told the warden, "Sure, I told them to put Rosenthal out of the way, but I didn't mean they should kill him. I wanted them to get him out of town so he wouldn't blab. Killing him was Rose's idea and the others. They wanted to save their own skins."
Jack Rose had served as a prosecution witness, as did
Harry Vallon,
Sam Schepps, and
Bridgey Webber. They were underworld criminal figures who were believed to be involved in the crime but were promised immunity by the district attorney's office in exchange for testifying against Becker. Charles Whitman, who was then
Governor of New York, signed Becker's death warrant in 1915 and attended the execution. On July 30, 1915, Becker was executed in
Sing Sing's electric chair by
John Hulbert, New York's
state electrician. The process took nine minutes, appearing to cause the man intense agony. For years afterward, it was described as "the clumsiest execution in the history of Sing Sing." Becker was interred at
Woodlawn Cemetery in the Bronx on August 2, 1915. He is buried next to his daughter. ==Controversy==