SALT LAKE CITY — Authorities are trying to determine how a pilot suspected in a homicide was able to slip into a small airport and steal an empty passenger plane that he drove into some cars.

He was later found dead in an aisle of the aircraft with a gunshot wound to the head.

SkyWest Airlines pilot Brian Hedglin used a rug to scale the razor wire-topped fence at St. George Municipal Airport early Tuesday. The plane crashed in an airport parking lot before it got off the ground.

Authorities were trying to determine just how Hedglin — who is wanted in the slaying of his girlfriend in Colorado — gained access to the 50-passenger plane while the airport was closed, among other details.

The short ride was jarring enough to collapse the plane’s front landing gear as it careened over landscaping, crossed a road, and hit a curb before crashing into cars in the parking lot, St. George police Captain James Van Fleet said.

He said investigators were still awaiting toxicology reports to determine whether drugs or alcohol were a factor.

He said they were also awaiting data from the cockpit recorder.

SkyWest officials said the company deactivated Hedglin’s access cards and put him on administrative leave after Colorado authorities named him a a suspect in the killing of his girlfriend, but declined to explain how he was able to steal one of their planes.

Van Fleet also said that once his officers had finished processing evidence on the plane, it was released to SkyWest, which painted over its logo and moved the aircraft back onto secure airport property.

SkyWest spokeswoman Marissa Snow said the jet was scheduled for a flight later Tuesday morning, but noted that it was empty and sitting on the tarmac when Hedglin, who had been a pilot for the airline since 2005, stole it.

The incident has raised overall concerns that the nation’s airports may not be as safe as they should be.

The Transportation Security Administration doesn’t require airports to maintain full-time surveillance of perimeter fences, leaving airport security largely in the hands of individual facilities.

St. George airport officials have said the small facility about 120 miles northeast of Las Vegas meets all federal security guidelines.

Van Fleet said that just one officer provides security for the airport as it is closed through the night until 6 a.m. the next morning when Transportation Security Administration officials and others return.

He said that his agency would be discussing whether additional security measures need to be added but noted that ‘‘this was a very determined person.’’

Dave Castelveter, spokesman for the Transportation Security Administration, said the agency was involved in the investigation, but declined to discuss specific security protocols, including how a plane is supposed to be secured when it is out of service, emphasizing that each airport has different security needs.

Representative Mike Rogers, Republican of Alabama and chairman of the Subcommittee on Transportation Security, said the incident ‘‘shows major security weaknesses at our airports that need to be addressed.’’

‘‘We have been pushing TSA to do a much better job overall of working with its partners, including airport authorities, to improve security,’’ Rogers said.