HOUSTON -

Family members of three victim's gunned down last year in a northwest Houston apartment are pleading for the help in finding their killer.

Houston police and the family spoke to the media about the unsolved triple murder that happened at 1325 Greens Parkway on the afternoon of April 17, 2013.

Police say 18-year-old Anthony Contreras, his wife, 18-year-old Elizabeth Mayorga, and their 5-month-old baby girl went to the apartment to visit Mayorga's uncle, Cesar Jose Enriquez.

Houston police say a co-worker of Enriquez later went to his apartment to check on him after he did not show up for work. The co-worker told police the front door was open and when he went inside, he saw blood on the walls of the bedroom. He called 911.

When Houston police officers arrived, they found the three adults and the baby in the bedroom. All of the adults had been shot in the head.

Officials say Mayorga and Contreras died at the scene. Enriquez, 36, was taken to Memorial Hermann Hospital where he later died.

"Right now we haven't made any arrests so we have a triple murder suspect out there on the loose, said Investigator Joshua Horn with the Houston Police Department. "This could happen to anyone's family."

Police say the baby was found under the bed and was not harmed during the attack. She was taken to an area hospital where she was treated and later released to family members.

"Hopefully someone doesn't go by another day with that burden with that guilt; hopefully someone will come and speak, and whatever that they know to call," said Pricilla Perez, Contreras' sister. "Anything will help. It is very important that justice will be brought. They had no reason to die at a young age. We just hope that someone comes forward."

As investigators work to figure out a motive, police believe at least one  of the victims, either Mayorga or Contreras, was an innocent bystander. 

Houston police say at this time, there is no known description of the gunman.

Anyone with information in this shooting should call the HPD Homicide Division at 713-308-3600 or Crime Stoppers at 713-222-TIPS.