Robert Anthony Rubio is being held for investigation of first-degree murder in the death of Troy Anthony Martinez, 21, who died of multiple gunshot wounds in the abdomen, authorities said Thursday.

Denver police arrested 26-year-old Rubio on Wednesday.

Gunshots were reported at 9:40 p.m. Tuesday at a home in the 1000 block of Alcott Street.

Rubio’s sister said she was on the phone with her younger brother, Jason Rubio, who was staying at the home with Robert Rubio, when a woman and two men entered the home and started beating Jason.

“He was screaming, ‘Help me! They’re jumping me,’ ” said the sister, who asked that her name not be used for fear of retaliation. She said she believes Robert Rubio was only defending his brother, himself and another friend who was staying with them. It was self-defense, she said.

Police found two men with bullet wounds.

The injuries to the surviving man, whose identity has not been released, were not considered life-threatening, police said.

Rubio has an arrest record for drug and assault charges.

He was convicted in 2005 and 2006 for misdemeanor charges of possession of drug paraphernalia. In 2008, he was charged with first-degree assault but pleaded guilty to a lesser charge of drugging a victim, according to Colorado Bureau of Investigation records. Also, Denver police arrested him July 31, 2009, on a felony assault charge, records show.

Martinez was killed the day after he turned 21. He too had a criminal record. In 2011, he was charged with aggravated robbery and convicted of a reduced charge of drugging a victim. He was placed on probation for five years.