This comes nearly a day after Deleon was back in jail for violating a bond condition.
Diamond's family members are expected to hold a press conference at 4 p.m. with FIEL executive director, Cesar Espinoza, outside the Harris County Courthouse on Franklin St.
"We are not happy with this decision and with the people who made this possible," Espinoza said. "Frank has proven to be a danger to the Alvarez Family. We had petitioned for him to remain in custody so that the family could be in peace. Diamond did not get a second chance, why should he? We need answers!"
According to police, Deleon was in a romantic relationship with Alvarez and another female. When Alvarez learned about the other relationship, she met Deleon at a nearby park, where he shot her, police say.
Prosecutors say Diamond was shot 22 times, mostly in the back.
Her family said the girl had left the home that night saying she was going on a walk with the family dog. She never returned home, but the dog did. Her family knew something was wrong and found Alvarez down the street with multiple gunshot wounds.
Among the conditions for his release, Deleon was required to wear a GPS monitoring device and abide by a curfew. However, according to a bond condition violation report, he was accused of failing to comply with the curfew requirement.
The Harris County District Attorney’s Office believes there was a glitch in Deleon’s GPS monitoring device. As a result, they believe Deleon didn’t actually violate his bond’s curfew requirements.
"I’m done," said Alvarez’s mother Anna Machado. "A glitch. A glitch on the system. A glitch didn’t kill my daughter. Frank did."
A bond hearing is scheduled for Thursday morning.