The Transportation Security Administration doesn't require airports to maintain full-time surveillance of their perimeter fences, leaving airport security largely in the hands of individual facilities.
At least one aviation security expert says it might be time to revisit those protocols.
"Maybe we need to implement some more levels of perimeter security because any type of security incident like this is a lesson to both the good guys and the bad guys. They read the papers just as much as we do," said Jeff Price, an aviation security expert and aviation professor at the Metropolitan State University of Denver.
The former assistant security director at Denver International Airport said that even after Hedglin gained access to the airfield early Tuesday, he shouldn't have been able to get aboard the plane.
"It should have been locked and secured if it wasn't in use," Price said.
TSA spokeswoman Jonella Culmer said the agency is "currently reviewing perimeter compliance" at the St. George Municipal Airport, which is about 120 miles northeast of Las Vegas.
City spokesman Marc Mortenson noted the airport is surrounded by six miles of perimeter fencing.
Local authorities were investigating the breach, but Mortenson said the facility meets all Federal Aviation Administration and TSA security requirements. He said, however, the entire perimeter isn't observed at all times, "and I would dare say it isn't at any airport in the country."
SkyWest spokeswoman Marissa Snow said Hedglin was a pilot for the airline since 2005 but had been on administrative leave since July 13, the day police found the body of his girlfriend and fellow Colorado National Guard member, Christina Cornejo, in Colorado Springs, Colo.
Authorities say she had been stabbed multiple times. Hedglin was the key suspect but had not been charged.
Colorado Springs police said they asked SkyWest to deactivate his access cards in case he showed up at the airline anywhere in the country. How the 40-year-old was able to gain access to the plane remained unclear.
The Gazette of Colorado Springs, citing court records, reported Hedglin dated Cornejo for four years and was arrested in March after he was accused of harassing her.
The records show that a restraining order was issued against Hedglin, and he was set for trial in August. He was released on $10,000 bond.
Attorney Steven Rodemer, who represented Hedglin in that case, said he was facing misdemeanor charges of criminal mischief, theft and harassment, but felony charges were dismissed Thursday.
Rodemer said he hadn't seen Hedglin since their last court date that day.
A police officer making rounds at the airport early Tuesday found a motorcycle with the engine running outside the perimeter fence, Mortenson said. As he searched for the owner, the officer came upon the idling plane and called SkyWest.
The airline sent an employee to turn off the engine. Inside, Hedglin was found dead with a gunshot wound to his head.
Snow noted that an inexperienced person could not have operated the plane, but she did not explain how Hedglin got aboard. "It involves sophisticated procedures and requires an extensive amount of training to even know how to start the plane," she said.
"If you defeat one layer of security, there are supposed to be other layers in place to prevent criminal or terrorist attacks," Price said. "Today, perimeter security at airports, it's just a fence. They're not required to have intrusion protection systems, and they're not required to have closed circuit TV to monitor the fence because the current level of risk doesn't warrant it.
"But maybe that needs to be looked at," he added.
Hedglin was a part-time soldier who worked as a cook in the Colorado National Guard. He had no specialized military training and was never deployed, Capt. Darin Overstreet said.
Cornejo was a full-time soldier who served in the Colorado Army National Guard's 100th Missile Defense Brigade in Colorado Springs. She enlisted in June 2006, became a second lieutenant last year and was named a distinguished honor graduate in two training programs. She had recently begun training as a current operations officer.
"She was an outstanding new officer who had already made a significant impact on our organization," her commander, Col. Gregory Bowen, said in a statement.
SkyWest officials said the CRJ200 plane Hedglin stole was not in service at the time. The aircraft is made by Bombardier and is capable of flying up to 534 mph with a range of 1,700 miles. Normally it has a two-person flight crew and a single flight attendant.
A dozen flights leave or arrive at the St. George airport each weekday, according to the airport's website. Most run between southern Utah and Salt Lake City, with two flights connecting St. George and Los Angeles.
Associated Press writers Holbrook Mohr in Jackson, Miss., and Colleen Slevin and Dan Elliott in Denver contributed to this report.