Mike enlisted in the U.S. Marine Corps in 1965, ultimately obtaining the rank of sergeant. His final tour of duty was spent in Vietnam in the DMZ as a ground motion picture photographer and during the siege of Khe Sahn.

On November 8, 1969 he married Mary Jo Critelli Hartnett of South Ozone Park, Queens. Later that year, Mike attended the University of Maryland, completing his education with a degree in Journalism.

The two moved to Brewster, NY which would become their home for the next 37 years.

Mike started his journalism career with the News-Times (Danbury, CT) covering Putnam County. He rose through the ranks eventually becoming editor. However, his greatest writing achievement was his involvement in the Brewster screenwriters group led by mentor and friend, Louisa Bisogno. During this time, he wrote three screenplays, each one presented as readings at the HBO theater.

In 2010, Mike and Mary Jo (or Watash as he called her) retired to Williamsburg, Va.

He leaves behind his wife Mary Jo, his son Christopher Hartnett and wife Kelsie Hamm Hartnett, grandson Mason Christopher Hartnett of Tomball, TX, his daughter Gillian Morgenthaler and her husband Darren Morgenthaler of Key West, Fla., his siblings Maureen, John and Philip along with loving Texas, Providence, R.I., Tappan, NY family, Williamsburg friends, and family in England and France.

His Bay Ridge buddies, Andy, Charlie, Jackie and Jimmy, his Marine Corps friends, Frank, Kurt Jon. His beloved sister, Mavis Hartnett Schaefer preceded him in 2004.

A memorial will be held in Williamsburg at Mike’s annual open house followed by a celebration of his life in Key West in May for family and friends. In lieu of flowers, the family asks any donations be made to the Wounded Warrior Project.org.