Shortly before 7 p.m. July 4, police received a 911 call reporting a body in the water near Cox Point Park, according to police spokeswoman Corporal Cathy Batton.
Gillis, of the 900 block of Lance Avenue in Essex, was reported missing on Tuesday. A 911 caller in the 500 block of Sandalwood Road told police there was a blue jetski floating near his boat without a rider, Batton said.
"The registration of the jetski showed that it belonged to the victim," Batton said. "We were unable to locate him at his home."
The US Coast Guard, Baltimore County police marine and aviation units and volunteer firefighters from North Point-Edgemere and Bowleys Quarters Volunteer Fire Departments but were unsuccessful in locating Gillis.
Gillis' body has been transported to the Office of the Chief Medical Examiner and is awaiting an autopsy, according to Batton.