The three Nassau Police commanders facing conspiracy charges -- William Flanagan, Alan Sharpe and John Hunter -- have more than 90 years' of combined service to the department.
Flanagan, 54, of Islip, served as second deputy commissioner in charge of a range of special police projects since 2009, officials said.
He was a driving force behind implementation of the gunshot detection system ShotSpotter, now deployed in some of the most dangerous parts of the county. He also helped organize police buybacks of illegal guns.
Flanagan also did some undercover narcotics work and was a trustee of the department's supervisors' union, officials said. He retired Wednesday.
Hunter, a 35-year veteran, was promoted to deputy chief of patrol last year.
A 27-year veteran, Sharpe was the former deputy commander of the Seventh Precinct Detectives Squad.
Sharpe, 54, of Huntington Station, held the rank of sergeant when he retired Jan. 6.