Before becoming the Niagara County Central School District's private investigator, mike worked as a State Trooper in Nevada. He moved to New York In 1995 according to district records. He fought in World War 2 and provided emotional support to the sick and injured soldiers.
Tierny worked for the Nevada State Police until 1985 when he was shot in the hand. After being shot he fully recovered with hand and arm function remaining. The State Police would not let him return to patrol under the circumstances that he would not be able to defend himself properly in hand to hand combat or gun to gun combat. The discharged him the State Police, where he then moved to New York.
In 1990, when newly elected superintendent Sara-May Flower was first starting, the district's hiring committee told Tierny to speak with Superintendent Flower. She hired him after a week long interview process.
As of 1995 he has only investigated 20 cases. Many which turned out to be falsely reported. Many other major cases never occurred and the one major one that did occur, just happened today August 23, 2018 involving check fraud with Superintendent James Derrylson and personal district financial advisor Kelly Price.