A Fairfield man was arrested Friday in connection with a fatal shooting in a Vacaville trailer park that was originally reported as a suicide, but was determined to have been a homicide, according to police.

Vacaville resident Ernesto Castillo, Jr., 19, was found with a single gunshot wound to the head in his trailer at the El Matador Trailer Park on Monday around 4:20 p.m., according to Sgt. Jeff King.

A male caller who contacted police told them that Castillo had shot himself inside the trailer.

Paramedics were unable to revive Castillo, who died at the scene.

Homicide detectives suspected from early on that the death was not a suicide, and that witnesses were not being forthcoming, King said.

After an investigation, police determined the shooting was a homicide, not a suicide, identified Fairfield resident Roberto Revelo as a suspect.

Revelo, 20, was arrested Friday on the 1900 block of Grande Circle in Fairfield. He was booked on suspicion of murder into Solano County Jail.