He is best known for his aggressive prosecution of the Hawaiian Mob during the mid 1980s, which took place after the murder of his son that was allegedly connected to organized crime.

While enrolled, he joined the US Navy Reserve Officers Training Corps as a rifleman and was subsequently deployed to fight in the Pacific Ocean theater of World War II.

[3] As a Naval commander, Marsland fought in the Philippines and, after the war, remained in the Navy as a prison administration officer at Pearl Harbor.

Following his discharge from the Navy, he returned to Tufts and graduated with his bachelor's degree in 1949, then enrolled at Northeastern University's school of law in Boston.

He attempted to run for his first elected office as Plymouth County district attorney, challenging incumbent John Wheatley.

During this period of his career, he developed a good rapport with the Honolulu Police Department which he carried with him to his next job as county prosecutor.