According to the Pinal County Sheriff's Office, Reynoso, 34, and De Santiago, 28, were shot and killed at their Mammoth home.
Investigators located their bodies outside, a few feet away from their house.
"It's been a very hard year for all of us. Hard to get through the day. Every single day I drive by the house where it happened. I give myself the sign of the cross twice. It's tough," said Joe Reynoso, Mark Reynoso's father.
Authorities believe the suspect(s) drove to the victims home in a midsize sedan or a midsize pickup truck.
Pinal County Victim Services, Silent Witness, and the family are offering an award of $5,000 for any info leading to an arrest in the double-murder.
"It's my gut feeling that it's somebody known to the family. It's extremely frustrating. I've gotten to know both sides of the family very well. I don't like having an unsolved case on the books, I certainly don't like not being able to fight for them," said Detective Joe Bonucci with the Pinal County Sheriff's Office. "We take pride in doing a good job here at the Sheriff's office and personally I don't feel that we've done that here."
"I've interviewed 50 some people in Mammoth over the course of this investigation. In all 50 the common denominator was we have a killer in this community. We are scared. This isn't the type of community where we lock our doors. You need to solve this because I'm locking my doors for the first time in 30 years," said Detective Bonucci.
Anyone with information on this crime is asked to call PCSO at 520-866-5105 or Silent Witness at 480-WITNESS, you can remain anonymous.