On Monday, Houston Police Department officials said the case is still active and the investigation is ongoing.
For Arlene's family, the wait for justice has been painful. Wendy and Armando Alvarez never thought they would have to bury their daughter.
"Our family hasn’t been the same since last year," Wendy said. "It breaks me how she was taken away from us."
It all started last Valentine's Day.
"Tomorrow’s the big day where we return to our nightmare," Armando said.
The family was heading to get food at their favorite pizza joint when Arlene was shot and killed while she sat in the backseat of her family's truck.
"As easy as it sounds, we thought it was going to be just another night, take my kids to Spanky’s where we eat there every weekend," Armando said.
It's a complicated case. A grand jury declined to indict the man who police said pulled the trigger. They said he didn't intend to shoot at Arlene.
Police said he was actually a victim himself and was firing his gun out of self-defense. According to investigators, that man was pulling money out of an ATM near the Gulf Freeway and the Loop when a man approached and robbed them at gunpoint.
The man who was robbed told police that when he got out of his car, he heard gunshots and believed he was being shot at so he fired at what he thought was the suspect's vehicle. It turned out to be the Alvarez family truck and Arlene was struck and killed.
"There’s a robber out there that started this tragic chain of events. I know we can find the killer. Somebody knows who he is," Harris County District Attorney Kim Ogg said.
Police said they have video showing the man they're looking for jumping a fence at a nearby business after the robbery.
Arlene's parents want everyone to see the video and want him to be caught.
"We are not giving up on my daughter’s case. We are still fighting for justice," Wendy said.
There's a $30,000 reward being offered in the case.
Ogg said the suspect will be charged with murder.
There will be a balloon release Tuesday morning at 9 a.m. at De Zavala Elementary, where Arlene went to school. At 11 a.m., there will be a celebration of life service at Immaculate Heart of Mary Church at 7539 Avenue K in Houston.