Shelly Holmes was treated at Washington County Hospital for smoke inhalation.
Ernst said then that neighbors reported seeing Holmes' Buick Skylark leaving the mobile home park at about 10:15 p.m. on June 27.
During the hearing Tuesday on whether evidence should be suppressed before the trial, Washington County Circuit Judge W. Kennedy Boone also allowed Ernst's findings from a search of Holmes' car.
Holmes' attorney, Assistant Public Defender Brian Hutchison, questioned Ernst about whether Holmes' statements were voluntary or forced.
Ernst testified that he found Holmes at about 8:30 a.m. on June 28 at Holmes' mother's mobile home on Amanda Lane, near Hagerstown.
Ernst said that after he identified himself to Holmes, and asked for his identification, he began questioning Holmes about the events of the night before.
Holmes said he had an argument with his wife but left before the fire occurred, Ernst testified.
On questioning from Hutchison, Ernst testified that Holmes said he could not write well. Ernst also said that Holmes did not sound like a well-educated man.
Ernst testified that he took a uniformed state trooper with him because Holmes' wife had said he might have a shotgun in his car. Ernst said Holmes smelled like alcohol from about three feet away, but did not sway or slur his speech.
Ernst said that because of Holmes' wife's indication that he might have a shotgun, and that he might have a gasoline can in his car, Ernst said he asked Holmes if he could search his car.
He said he verbally verified with Holmes three times that he could search the car, after which Holmes showed Ernst the inside of the trunk and car, Ernst said. There was no shotgun or gasoline can inside the car, Ernst said.
Ernst said the interview and search took about 10 minutes.
Holmes did not testify during the hearing.
After arguments from Hutchison and State's Attorney M. Kenneth Long, Boone said he believed Holmes' statement was voluntary and unaffected by "the fact that he could not spell or write well - was not a learned person - or having been hung over."
Holmes is being held without bond at the Washington County Detention Center. His trial is scheduled for Dec. 3.