DENVER (CBS4) — A Denver family desperate for new leads in the deadly shooting of 17-year-old Diego Marquez last September is now increasing the reward for new information leading to the killer.

Diego Marquez was killed Saturday, Sept. 21 at Green Valley West Ranch Park in Denver (credit: Denver Police)

“I’m not going to have peace until we get somebody arrested and locked up,” said José Marquez, Diego’s father. “I want justice for my son and I’m doing everything possible.”

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During a news conference Thursday morning, Marquez announced the reward for information leading to Diego’s killer has increased to $10,000. Marquez contributed his own money, hoping it will bring in more tips.

“I don’t have my son and these individuals are enjoying the holidays and doing all this stuff. My son’s not around,” said Marquez.

According to DPD, Marquez’s death is being investigated as a homicide. He was found shot dead on Sept. 21, at East 45th Avenue and Argonne Street in Green Valley West Ranch Park. Detectives are confident someone in the area has more information.

green valley ranch west park homicide denver police

Denver Police investigate a homicide at Green Valley Ranch West Park. (credit: CBS)

Denver Police says there was a call overnight of shots fired. Officers checked it out, but didn’t find anything. The next morning, a person who came early to prepare the fields for a football game found Diego’s body and called police.

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Marquez recalls overhearing his son in a heated discussion before the shooting.

“I heard him screaming and hollering. He was upset. He wouldn’t say anything. He wouldn’t tell me anything,” said Marquez.

He’s pleading for anyone who might be on the fence about coming forward or with any amount of information to help.

“I just want them to know that I miss my son. My whole family misses my son. We just want justice for my son and those individuals just off the street. Because, like I said, if they did it to my son, they can do it to someone else. Who knows if they’ve done it before?” José Marquez said.

Police said they don’t have a description of any suspects but they are asking witnesses who saw anyone running away from the area or cars leaving the scene the night of the Sept. 20 or morning of the Sept. 21 to please contact Agt. M. Ingui at 303-739-6067.

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Tipsters can remain anonymous and be eligible for a reward of up to $10,000 by calling Metro Denver Crime Stoppers at 720-913 STOP (7867).

Tori Mason