The San Antonio police department arrested 22-year-old Eric Trevino, who they believe is responsible for the capital murder of 3-year-old Rene Blancas back in November.

Rene Blancas

Rene and his baby sister, 1, were both in the backseat of his family's car when a bullet struck and killed him on November 4.

“I made a promise...a few months ago when the shooting first happened that we would make an arrest, and today we kept our promise,” SAPD Police Chief William McManus said.

Mcmanus said police received a tip that led them to arrest the 22-year-old suspect in the 1300 block of Cupples Road on the southwest side Wednesday afternoon.

The victim's parents Rene Blancas Sr. and Melanie Santos said the weeks-long wait for a break in the case was painful.

"We're going to have to live with seeing that Monster," said Santos. "I want to forget his face but we're always going to see it."

Rene Blanco Jr. died three days before his fourth birthday.

Trevino reportedly had five outstanding felony warrants and two misdemeanor warrants.

"When I saw the guy, I felt so sick," said Santos. "Sick to my stomach. Like I felt angry. He took an amazing life away. He was such a loving little boy. He had a beautiful smile. I just want to know why."

Police have not released a motive and the murder weapon has not been recovered.