AURORA, Colo. (KDVR) — The brother of a man suspected of killing four people at an Aurora home has been accused of being an accessory to the murders.

Juan Angel Castorena, 18, was arrested Friday on suspicion of being an after-the-fact accessory to first-degree murder, according to the Aurora Police Department.

Police say there is no evidence that Juan Castorena was involved in the shootings, but they did not immediately say what exactly led to his arrest.

Meanwhile, his 21-year-old brother, Joseph Mario Castorena, is the primary suspect in the killings and remains wanted on four counts of first-degree murder. Investigators are offering a reward of up to $15,000 for information that leads to his arrest.

Police urge anyone who sees Castorena to call 911 immediately. Tipsters who have information that could lead to his arrest can contact the Metro Denver Crime Stoppers tip line at 720-913-7867 or submit a tip online. Tips can be anonymous.

A history of violence before deadly shootings

The shootings were at the home of Joseph Castorena’s ex-girlfriend, where the family said they got home from a party early Sunday morning, not knowing he may have been waiting inside the Geneva Street home.

Mariana Serrano and her husband, Ken Green, were two of the four people killed. Mariana Serrano is the sister of Castorena’s ex-girlfriend. Their father, Jesus Serrano, also was killed, along with neighbor Rodolfo Salgado, family members have said.

Castorena’s ex-girlfriend survived the shooting by hiding in a bathroom with her sister’s two young daughters. Both she and her father were granted temporary protection orders against Castorena just last week. They claimed Castorena had previously threatened to kill members of the family and was physically abusive, meaning he wasn’t allowed to be near their home.

Castorena also has a pending case on charges of child abuse. He was arrested in August 2020 after his then 3-month-old child was brought to Children’s Hospital Colorado with a broken arm. Hospital staff discovered the infant also had skull fractures.