DENVER — The man accused of killing three people near a south Denver light rail station was after an unpaid drug debt, documents show.

Maurice Aaron Butler, 38, also known as Khaos, is charged with three counts of first-degree murder.

Prosecutors allege that on Aug. 9 near the light rail station at South Broadway and Interstate 25, Butler shot and killed 28-year-old Nicole Boston, 39-year-old Jerome Coronado and 45-year-old Christopher Zamudio.

Police believe all three were transients.

According to an affidavit and arrest warrant, investigators found three .22 caliber fired cartridges at the crime scene, which was described as a homeless camp.

An autopsy performed by the Denver Office of the Medical Examiner determined all three victims died from gunshot wounds to the head consistent with the cartridge casings found at the scene.

A homeless woman told detectives that Coronado, who she also knew as “Rome,” was in trouble over a drug debt.

Moreover, the woman said Coronado told her he had to hide his girlfriend, Boston, because the drug dealer was looking for her.

The Denver Police Department also interviewed a man who said he met with a man he identified as “Roman” about 10 days before the homicide.

Roman told him he was afraid for his girlfriend’s safety and owed someone $100.

The man also reported he saw Roman with a black eye two or three days before the homicides. He said Roman told him that he was going to be killed if he did not pay the debt.

A third person, who police described as a “well-known transient in the area,” said “Rome” came to her about one week before the homicides looking for protection for himself and his girlfriend, “Niki.”

The woman also reported that Rome had a black eye, but said she assumed Niki had beat him.

The woman reported she told Rome to go to the Sinclair gas station at Alameda Avenue and Broadway to call police. However, police said there is no evidence the victims contacted law enforcement.

A fourth interviewee, who works at the gas station, said Boston had expressed concerns about owing a drug dealer money.

The Sinclair employee said Boston told her that her boyfriend had “fronted some ‘black,’ which is slang for heroin, and he had still not paid the dealer for the heroin,” according to the affidavit.

Boston also told the gas station worker that her boyfriend had been beaten up and received a back eye over the debt.

Other witnesses told police that a man known as “Khaos” matched Butler’s description and was known as a drug dealer in the area, according to the documents, which included a number of redactions.

Police said Butler was on parole after a 2010 incident in which he kidnapped an at-risk adult who had been buying drugs from him. Butler then tried to extort $500 from the victim’s family.

Detectives issued a parole violation warrant after speaking with Butler’s probation officer. Officers located him quickly because he was wearing an ankle monitor.

In the documents, investigators said information on Butler’s phone corroborated information that Boston and Coronado were in debt to Butler at some point.

Using GPS data from his ankle monitor, detectives were able to place Butler at the site of the homicides during the time in which they were believed to have happened.

Police also obtained surveillance footage that they believe matches other evidence placing Butler at the scene of the homicide.

“During this investigation, your affiant has learned that Nicole Boston and Jerome Coronado were homeless drug addicts who often bought their drugs at Civic Center Park. Maurice ‘Khaos’ Butler is a self-admitted drug dealer primarily in the Civic Center Park area,” the document reads.

Investigators said Coronado and Boston had been living near 13th Avenue and Umatilla Street before moving into hiding out of fear of what Butler might do to them over the drug debt.

“There is no evidence of a disturbance or any type of resistance from the victims and there is no evidence of a robbery. It appears that all three victims were executed,” the document reads.

Butler was arrested on Sept. 6. The documents did not elaborate on Zamudio’s connection to others in the case.