The trooper testified that Catlett told him he shot Mason more than once.
The case against Catlett, 21, of Rt. 2, Box 389, Hedgesville, W.Va., was sent to the grand jury following the hearing before Magistrate Harold "Gene" Darlington.
Police said they have no motive for the killing.
According to testimony, Mason's body was found in a pool of blood on the floor of his kitchen around 10 a.m. on Feb. 4, by John Ashley, Mason's roommate. Both worked at County Market in Hagerstown.
An autopsy showed that Mason died from two bullet wounds to the head, according to testimony.
Catlett told police that he threw a rifle into Back Creek, Laing said A search of the area has not turned up a weapon, Laing said.
Laing also testified that Catlett's mother, Cynthia Young, had reported that her home had been burglarized and that a .22-caliber rifle stolen.
Laing said Catlett told police he went to his mother's house, took a shower, and changed his clothes. Laing said police tied the two crime scenes together and found blood-soiled clothes at Young's house on the day Mason was killed. Mason's trailer and Young's house are only five minutes apart, Laing said.
Catlett, who has a history of mental disorders, has been hospitalized twice for the condition, according to court records. Catlett claimed he could communicate with UFOs, court records said. Catlett also has a history of drug and alcohol abuse, although neither figured in the crime, according to Laing's testimony.
Public Defender Jerry Dambro said after the hearing he is considering an insanity defense for Catlett.
"We're going to have a complete psychological workup done on him," Dambro said.
Last week, Catlett tried to bolt from custody while he was being fingerprinted, police said. He was calm in court Monday, although his right leg shook at times.
Several of Catlett's relatives, including his mother, were in the courtroom.