Authorities said Marissa Mion’s two young children were nearby when the July 5 shooting occurred in Oshtemo Township.

OSHTEMO TOWNSHIP, Mich. — A 32-year-old Michigan man is accused of fatally shooting the mother of his children inside their shared home, days after witnesses said he threatened to kill her if she did not remain with him, according to court records and local news reports.

Ernesto Cuascut-Santini was charged with open murder and firearm offenses following the July 5 death of 25-year-old Marissa Mion at the Colonial Manor Mobile Home Park in Kalamazoo County. Deputies said Mion was shot at least eight times. The couple’s children, ages 1 and 7, were in another room of the home, according to court documents cited by WWMT. Cuascut-Santini has not been convicted, and the allegations against him will have to be proved in court.

The Kalamazoo County Sheriff’s Office was sent to the residence shortly after 3:30 p.m. after receiving a report that Mion had been shot. Deputies found Cuascut-Santini outside the home with what investigators described as blood spatter on his face. Mion was found on the floor of a bedroom with multiple gunshot wounds. Court records cited by FOX 17 said a responding sergeant heard Cuascut-Santini say that he had shot his girlfriend. The emergency call did not come from a witness inside the home, according to the published accounts. Investigators said Cuascut-Santini called his sister and a friend after the shooting and told them what had happened. His sister then contacted authorities at about 3:30 p.m. The reported calls became part of the sequence investigators used to describe the minutes after the gunfire and before deputies arrived at the mobile home park.

During a later interview, Cuascut-Santini allegedly told investigators that he shot Mion multiple times after an argument. Another report, citing information attributed to investigators, said he told authorities he fired until the gun was empty. That account remains an allegation contained in reporting about the investigation and has not been tested at trial. Authorities have not publicly released a complete recording or transcript of his interview.

An autopsy added another important piece to the case. Deputies said eight bullets were recovered from Mion’s body and that her wounds showed she had been struck by additional gunfire. The finding led authorities to describe the shooting as involving more than eight shots. Officials have not released a full autopsy report in the materials reviewed for this article, and no further forensic findings have been publicly detailed.

Investigators also gathered accounts of conflict before Mion’s death. Witnesses reportedly said the couple had been arguing in the days leading up to the shooting. One witness told investigators that Cuascut-Santini had threatened Mion several times, including an alleged warning that she would either remain with him or he would kill her. The statement is central to the prosecution’s reported account because it describes an alleged threat shortly before the fatal encounter.

A friend of Mion told local media that the relationship had ended and resumed more than once. According to reporting that cited the friend’s account, Mion was attempting to collect her children and personal belongings from the home on the day she died. She reportedly asked the friend to monitor her location because she was worried about her safety. Authorities have not publicly explained whether anyone was watching the location information at the moment of the shooting or whether it became evidence in the case.

The same reporting said Cuascut-Santini told investigators that he had thrown away some of Mion’s clothing before she arrived. An argument followed, according to that account. He also allegedly described weapons as having appeared during earlier disputes between the couple. The available reports do not provide independent documentation of those earlier incidents or say whether police had previously been called to the home. Investigators have not announced whether any earlier reports, messages or recordings are part of the prosecution’s evidence.

The presence of the children is another major element of the case. Court documents cited by WWMT said the 1-year-old and 7-year-old were in a nearby room when Mion was shot. Authorities have not released their names, described what they may have heard or seen, or disclosed who assumed their care afterward. News organizations have generally withheld identifying information about the children because of their ages and the circumstances surrounding their mother’s death.

Cuascut-Santini was booked into the Kalamazoo County Jail on July 5. The sheriff’s inmate inquiry listed him as being held without a posted bond amount and recorded a homicide-related charge. Prosecutors formally charged him two days later, according to local reporting. Michigan’s open murder charge allows prosecutors to proceed without selecting a specific degree of murder at the initial charging stage, leaving the final classification to later court proceedings based on the evidence presented.

Charging documents represent the government’s allegations and are not findings of guilt. At future hearings, prosecutors will be required to present evidence supporting the charges, and the defense will have an opportunity to challenge witness statements, forensic conclusions and any alleged admissions. The reviewed reports did not identify an attorney speaking on Cuascut-Santini’s behalf or provide a defense response to the accusations. They also did not establish whether he had entered a plea beyond the routine early stages of the case.

As the investigation moved into court, Mion’s relatives asked the public to remember more than the circumstances of her death. Her brother, Brandon Mion, described her as a devoted sister, mother and friend who was compassionate, resilient, smart and funny. Her aunt, Cyndi Thomas, said Mion would have wanted to be remembered as a caring mother rather than only as a victim of violence.

Relatives said their last gathering with Mion took place on the Fourth of July, one day before the shooting. She brought banana pudding and remained with the family through the fireworks. Friends said she took pride in making her children happy and worked to give them experiences and stability. An obituary cited by True Crime News said she enjoyed reading, shopping, video games, cooking, travel and fitness and worked with adults with disabilities.

Those memories stand beside a developing criminal case built, according to published accounts, from the scene, the autopsy, witness interviews, the alleged threat and Cuascut-Santini’s reported statements. Some evidence may not become public unless it is introduced during a hearing or trial. Authorities have not announced a final determination about motive beyond the relationship conflict described in the court records and witness accounts.

Cuascut-Santini remained listed in the Kalamazoo County Jail inmate system when the record was reviewed. The available public reports did not establish the outcome of any hearings scheduled after his arraignment or identify a confirmed trial date. The open murder and firearm allegations remain pending, and Mion’s family continues to mourn a mother of two whose life, relatives said, should not be reduced to the violence that ended it.

Author note: Last updated Aug. 4, 2026.