Demarea Harris and Dexter Lewis walked into the bar first.

The two cased the room — where five people were present — to make sure it was prime for a robbery. Harris stood in the back of the bar when his two friends entered wearing superhero masks, and he waited as the other men ordered everyone to lie face down on the floor. He watched as each victim was stabbed at least 10 times.

One of Harris’ accounts of that night claims he dashed out the back door after the five people were stabbed to death at Fero’s Bar and Grill in October 2012. But Harris has been pinned as a liar by attorneys, and even detectives on the case have acknowledged he lied to federal agents and gave inconsistent details about that night.

More than 15 months later, two men have pleaded guilty and received lengthy prison sentences, and a third faces the death penalty. But Harris has not only been spared any charges, he quickly disappeared behind the dense and mysterious curtain of protection that draws around those working for federal agencies.

Harris was a confidential informant for the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives on an unrelated investigation when he entered the Denver bar with Lewis and brothers Joseph and Lynell Hill. Little is known about Harris’ history, his relationship with the ATF, any compensation he was receiving and whether his relationship with the Hill brothers or Lewis was connected to his role as an informant.

Even attorneys representing Lewis and Denver prosecutors seeking the death penalty have learned little about Harris.

Federal regulations heavily protect federal law enforcement employees and cases, especially in instances involving confidential informants whose often less-than-reputable histories allow them into the inner circles of criminal activity, said Eugene O’Donnell, a former police officer and prosecutor from New York City.

“You are using such people usually because you must not because you would like to,” O’Donnell, who now teaches law and police studies at John Jay College of Criminal Justice, said in an e-mail. “They frequently have backgrounds which run from minimally unsavory all the way to utterly despicable.”

The only details available about Harris’ actions the night of the stabbings were provided by Harris and Joseph Hill. Almost 10 hours after firefighters pulled the victims’ bodies out of the burning bar, Harris met with his contacts at the ATF.

Denver police investigators interviewed him about three hours later.

In July, Denver prosecutors announced they are seeking the death penalty against Lewis, and the Hill brothers accepted plea agreements in exchange for testimony against Lewis. A protective order for Harris has been filed under seal. It is unknown whether Harris remains in Colorado and whether he is still providing the ATF information.

The arduous process of requesting information about some federal cases may keep either side from ever obtaining records about Harris.

A 1951 ruling by the U.S. Supreme Court makes it difficult for attorneys in district court to obtain information about informants for federal agencies, said Nancy Leong, a professor a the University of Denver’s Sturm College of Law. Filing a formal request is generally the most successful method, Leong said.

Neither defense attorneys nor prosectors have filed such a request. On Jan. 7, Denver District Court Judge John W. Madden IV quashed two defense subpoenas for ATF agents connected to the case.

“A court is reluctant to deviate from the normal process,” Leong said.

It’s not clear what role, if any, Harris would play at Lewis’ trial, but Lewis’ attorneys will probably continue challenging his credibility.

“Complicating an accurate assessment of a (confidential informant’s) veracity is the knowledge that — typically — they have chosen to put their interests over everyone else’s,” O’Donnell said. “Those who break the law are commonly not caught for all or even most of their crimes. That deception, denial and deceit are wielded unflinchingly.”

During the preliminary hearing last February, Detective Mark Crider testified that Harris told ATF agents inaccurate details, according to a defense motion. Joseph Hill’s attorney, Tom Hammond, called Harris a “proven liar.”

According to search warrants, Harris said he ran out of the bar as he saw the three other men pouring alcohol on the bodies. On Jan. 7, however, Lewis’ attorneys suggested it was Harris’ idea to burn the victims.

Lewis faces 16 counts, including first-degree murder, in the deaths of the bar’s owner, Young Suk Fero, 63, of Aurora; Daria M. Pohl, 21, of Denver; Kellene Fallon, 44, of Denver; Ross Richter, 29, of Overland Park, Kan.; and Tereasa Beesley, 45, of Denver.

Lewis’ attorneys say they want to know why their client could face the death penalty, while Harris has been allowed to walk.

“We want information for why he has been exempt,” Public Defender Christopher Baumann said at a hearing earlier this month. “This information is exculpatory for guilt and the death penalty.”

Jordan Steffen: 303-954-1794, jsteffen@denverpost.com or twitter.com/jsteffendp