Days later, he was cremated. His ashes arrived in his grandparents' mailbox.
Lopez had been serving a sentence of up to 15 years in prison for aggravated robbery and failure to respond to a police officer, according to court documents. But family members said he wasn't a violent man.
Why then, the mother asked, was Lopez put in a prison cell with Jacob Paul Ecker, a man with a long history of mental illness and violent offenses?
Ecker, 24, was sentenced Tuesday in 3rd District Court to prison term of five years to life for killing Lopez.
The sentence will run concurrently to the zero to five years he has been serving on a number of felony counts stemming from a March 2010 incident in which he threatened a man's life at the Salt Lake City Main Library while carrying a hatchet in his backpack, according to court documents.
"If he suffers from all this mental illness ... the prison should have known to put him separate from the rest of the world," Martha Lopez told Judge Mark Kouris between sobs. "I hope he is put away in a corner somewhere, away from everyone. Because thanks to him, I'm not ever going to see my son again."
Due to privacy laws, the Department of Corrections could not comment specifically on Ecker's mental health.
But spokesman Steve Gehrke said, "Officers rely on all the information at hand when it comes to making housing decisions from gang intelligence and criminal history to mental health status and even an offender's stated preferences or concerns."
Inmates with mental health issues must undergo several in-house screenings with experts to determine when they can move to general housing, Gehrke said. This happens only when the mental health unit is "confident" that the inmate is stable.
Ecker told the court Tuesday that he and Lopez were friends, and the pair had requested to bunk together. He regrets every day what happened.
"I can't take it back; I wish I could," Ecker said. "I deal with pain every day knowing I killed one of my friends. I think I need to be put away for a long time, too."
As he spoke, Martha Lopez covered her ears. Her gaze bore into the ground. She would not look at the young man with the short pony tail and tear-drop tattoo who stood at the front of the room.
She's a long way from forgiveness.
"Nothing that person says is going to bring my son back," she told the judge. "Nothing anyone says will bring him back."
According to testimony at a preliminary hearing in November, tensions between the two men came to a head when Ecker "let loose" on his friend, punching him twice.
Lopez fell to the ground and Ecker continued to attack him, a Unified Police detective testified.
Lopez suffered a collapsed lung and a lacerated heart and liver as a result of the attack. He died of internal bleeding.
Defense attorney Wesley Howard said Ecker acted in self-defense after Lopez had grabbed a pen to use as a weapon. There were no eyewitnesses to the attack.
Lopez's family had never before heard this characterization of events. They said they don't believe a word of it.
"Everything [Ecker] said in there is a lie," sister Christina Lopez said after the hearing. "If he did that to my brother in jail, imagine what he could do if he ever gets out."