Mike is an engineer (with a both undergraduate and graduate degrees from MIT in Mechanical Engineering) who worked as head valet for the first Season, but was then recruited by Ed Deline to the security department to help during Danny's military absence. He stayed on as security personnel despite being paid less than his job as a valet and cured his claustrophobia in the end of season one. Mike and Danny are best friends. In Season 5, when Danny accepts the job as the President of Operations for the Casino, Mike is promoted to Head of Security and Surveillance. (wikipedia.org)