Investigators say the shooting followed weeks of conflict, angry messages and an earlier gun threat never reported to police.
WADDELL, Ariz. — Authorities say the fatal shooting of Heather Marin in a garage west of Phoenix unfolded against the backdrop of a crumbling marriage, a pending divorce and earlier threats involving a gun, turning a family separation into a homicide case now centered on Robert Marin.
The public record in the case does not describe a sudden, isolated dispute. Instead, investigators say the marriage between Robert Marin, 60, and Heather Marin, 50, had already deteriorated into fear, hostility and unresolved violence by the time deputies were called to the home near Olive Avenue and Perryville Road on March 16. That larger backdrop helps explain why prosecutors pressed for a high bond and why investigators treated the daughter’s account and the family’s recent history as central pieces of evidence.
According to the probable cause affidavit, the couple had separated informally and were in the process of divorcing. Their teenage daughter told investigators she argued with her father earlier that evening and that, during the argument, he spoke with hatred about Heather Marin. She said she later overheard him on a heated call with Heather, telling her he could not deal with their daughter and did not want the girl to stay in the house. The affidavit says the daughter then withdrew to her room, called her boyfriend and ignored two calls from her mother, one at about 8:39 p.m. and another at 9:09 p.m., because she feared answering would worsen the tension inside the home.
Police say the conflict reached its end in the garage. After the missed calls, the daughter reported hearing screaming, then her mother pleading, “Please don’t kill me, please don’t kill me,” before about four gunshots. When she opened the interior door, investigators say, she found Heather Marin bleeding on the floor and Robert Marin standing near or over her with a firearm. The daughter shouted, “Why would you do this?” according to the affidavit. Investigators wrote that he shrugged his shoulders and later smoked a cigar while she tried CPR and called 911. Deputies who arrived around 9:30 p.m. reported blood on his clothing and shoes, along with a gun, holster and spent casings in the garage.
What gives the case additional weight is what the daughter said had happened before. She told deputies about an unreported domestic violence incident in early February in which her father allegedly held a firearm, threatened to shoot Heather Marin in the head and threatened to kill himself. She also described screenshots of text exchanges between her parents that investigators said contained threatening and hateful language. The affidavit says she told deputies her father was an avid gun owner who kept multiple unsecured firearms throughout the home, including pistols and hunting rifles, with more guns and ammunition in a safe. None of those earlier allegations have been proved in court, but they provide context for why investigators quickly framed the killing as part of a pattern rather than a single outburst without warning signs.
The couple’s daughter also appears to be the person who links the family history to the final minutes of Heather Marin’s life. Her account speaks to the emotional climate in the house, the immediate trigger involving where she would stay, the angry call that drew Heather to the property and the sounds she heard moments before the shots. Investigators will likely compare that narrative with phone records, dispatch timestamps, forensic analysis of the gunfire and the medical examiner’s findings. The open record still leaves gaps, including how long Heather was at the home before the shooting and whether any other adults knew she was going there.
The prosecution now moves into its formal stages with those family-history allegations hanging over it. Local reporting on Marin’s first appearance said he faced a first-degree murder count and was held on a $2 million cash bond. A later report said a direct complaint listed second-degree murder and two disorderly conduct counts. Whatever final form the charges take, the state is expected to rely on the mix of family testimony, physical evidence and earlier alleged threats to explain intent and danger. Defense lawyers, in turn, can be expected to test whether those earlier incidents are admissible and how much they actually prove about the shooting itself.
This case now stands as the fatal end of a separation that records say had been growing more volatile for weeks. The next public marker is the court filing that confirms the operative charges and the next hearing date in Maricopa County.
Author note: Last updated April 9, 2026.