Walsh was a former police officer, who had started working as Catherine Weaver's personal investigator.
His father was a Long Shoreman who worked on both the east and west coasts. He met and married his mother in San Fransico. Welsh was born in L.A. He had an uncle who lived in L.A. and worked as a security guard at a local L.A. trust company and also an aunt who was living in Baltimore. At age six, his family moved back to Baltimore to be with other family members. After his mother died, he and his father moved in with his aunt. After graduating from a Baltimore High School, he used his father's and his L.A. uncle's references to get a job working as a Baltimore Long Shore Port security guard for two years. With some financial support from his aunt, he then completed the required two year police academy training prior to joining the Baltimore Police Department, where he served for 23 years. At age 45, he was forced to take early retirement when a possible case of misconduct and malfeasance occurred which would have implicated him. In spite of this incident, he continued to poudly wear his long service Baltimore PD ring.
After leaving the Baltimore Police Department, in late 2007 he received an anonymous call from the Zeira Corporation stating that they would like to meet with him to discuss employment of his services to investigate certain corporate problems that the company has been having. Not having seen California for some time, he met with Catherine Weaver who persuaded him to help her locate missing property and also find and acquire new proprietary technology for Zeira Corporation. Using his previous police "contacts", Walsh was able to locate and acquired the Turk, and sold it to Catherine Weaver at Zeira Corp headquarters for 300,000 dollars.
Weaver sent Walsh to track down the whereabouts of George McCarthy, an employee of the "Desert Canyon Heat and Air" facility in the high desert, who had been listed as dead after the destruction of the facility. Walsh went to the company town, and attended the vigil and wake for the deceased townspeople, searching for clues. Derek Reese recognized that Walsh wasn't a regular mourner, and offered to give him a ride to the funeral. In the truck, Walsh pretended that he was an OSHA investigator trying to determine the cause of the plant explosion. Realizing that Reese was also searching for information on the plant, Walsh got out of the truck and walked the rest of the way to the funeral.
After the funeral, Walsh walked to a house in the neighborhood, secretly tailed by Sarah Connor who had learned from Reese that Walsh was looking for something. He broke into an empty house and disappeared inside. The house contained a secret surveillance room, used by George McCarthy, and a tunnel which led to McCarthy's garage. Walsh was killed and his body was left by a pond outside of town. Some of his blood was found in the surveillance room by Sarah Connor who had followed him to investigate.
That evening, Sarah, John, Cameron, and Derek found Walsh's bloody body by the pond, along with some of the dead cows that John and Cameron had viewed earlier in the day. As they were examining the scene, the drone lifted out of the pond and flew away.
Behind the Scenes
- The line about formerly being a member of the Baltimore Police Department, 4th Precinct in the episode "Desert Cantos" is a direct reference to actor Max Perlich's previous role on the TV show Homicide: Life on the Street about the 4th Precinct of Baltimore PD, even though Perlich's character on that show, J. H. Brodie, wasn't actually a cop, but a reporter and later a crime scene recorder.