According to court records and police, a long-running family court dispute involving allegations of abuse, neglect, and firearms restrictions preceded a murder-suicide on Mercer Island and two additional deaths in Issaquah now under investigation.
King County court records of those events match the Mercer Island home.
On Tuesday morning, Mercer Island police responded to a welfare check at a home in the 8400 block of Southeast 46th Street after an attorney representing the homeowner reported receiving a concerning email that raised fears for the occupants’ safety.
That attorney has confirmed to KIRO 7 News that two of the victims are Danielle Cuvillier and her son, Dominick ‘Nick’ Cuvillier.
In a statement provided to KIRO 7 News: “Danielle’s friends and family are in a state of shock, grief and utter disbelief at the news of her and her loving son Nick’s deaths. We need time and space to mourn appropriately and will release a full statement when we have had time to process this devastating sequence of events.”
It’s believed that three of the four victims are mother and sons.
Officers arrived around 10:45 a.m. and saw a body through a window, prompting them to enter the home.
Inside, police found a woman in her 70s and a man in his 40s dead from gunshot wounds.
Investigators said the deaths are being investigated as a murder-suicide.
According to the Mercer Island Police Department, they have been identified as Danielle and her son, Mackenzie ‘Mack’ Williams.
No forced entry was reported.
Investigators found four firearms inside the home and an additional firearm inside a vehicle.
While investigating the Mercer Island deaths, detectives identified concern for another individual who had previously lived at the home.
As a precaution, Mercer Island police contacted Issaquah police to conduct a welfare check at a residence on Southeast Evans Lane.
Issaquah officers arrived at that location around 11:37 a.m. and found a woman in her mid-40s and a man in his mid-30s dead inside the home.
There were no signs of forced entry, and police said there are no outstanding suspects.
Neighbors told KIRO 7 that the woman found dead in the Issaquah home was Williams’ wife.
Investigators have not determined which deaths occurred first, and the relationship between the two households has not been publicly disclosed.
The King County Medical Examiner will determine the official cause and manner of death in all four cases.
The investigation remains ongoing.
Court records provide background
Court filings in King County Superior Court show that, in the weeks leading up to the deaths, the Mercer Island home was the subject of a contentious vulnerable adult protection order case involving close family members.
The filings describe Nick as a severely disabled adult with Angelman syndrome, a rare genetic condition that causes developmental delays, limited speech, impaired coordination, and a need for nearly constant supervision.
Court documents state Nick required assistance with basic daily tasks, including feeding, hygiene, and mobility, and has lived with family caregivers throughout his life.
In late January, Danielle petitioned the court for a protection order against Nick’s brother Mack after an alleged assault on Jan. 16, alleging exploitation, aggressive behavior, and improper removal of Nick from her home.
The petition requested restrictions on contact and sought a court-ordered surrender of firearms, citing concerns about safety.
Mack filed a detailed sworn declaration disputing those claims.
In that filing, Mack described a shared caregiving arrangement that began after their father’s death in 2018 and said he became increasingly concerned about Nick’s physical injuries, stress behaviors, and access to medical care while living with their mother, Danielle.
The declaration alleges a pattern of physical, verbal, and emotional abuse toward Nick over several years, along with concerns about alcohol use and delayed medical treatment.
Mack stated those concerns escalated in late 2024 and early 2025, culminating in a confrontation at the Mercer Island home on Jan. 16.
According to the declaration, Nick was scheduled to visit Williams on Thursday, Jan. 16, 2025, a routine arrangement in which Williams would pick Nick up in the morning and return him later in the evening. Late the night before, Williams said he received a text message from Cuvillier stating the visit would not take place. When Williams asked for clarification, he said he did not receive a response. Willaims docs Triple Murder Sui…
Williams wrote that the sudden cancellation and lack of explanation raised concerns about Nick’s wellbeing. He said Nick had been increasingly asking to live with him and had recently shown signs of physical injury and stress-related behaviors.
According to the declaration, on the morning of Jan. 16, Mack went to Danielle’s home to check on Nick.
In the declaration, he states that his mother initially refused to let him enter the home or see his brother.
Mack said he told her he would call police to request a welfare check if he could not verify Nick’s condition.
Mack called 911, and during the call, Danielle allowed him into the home.
Mack stated that when he located Nick, his brother showed him an injured foot and complained of pain related to a prior back or hip injury.
While Mack was on the phone with the 911 operator, a verbal argument continued.
The declaration describes the situation escalating into a physical altercation.
Mack alleges that Danielle attempted to interfere with his 911 call and struck him.
He states he pushed her away to protect himself and Nick.
During the struggle, Mack alleges that Danielle grabbed Nick’s arm while trying to take the phone from him.
Police responded to the home and interviewed both parties.
According to the declaration, officers determined that Danielle was the primary aggressor and arrested her on suspicion of domestic violence.
She was taken to jail and released the following day.
Mack said he took Nick with him when he left the home that day, with police present.
Mack sought medical care for injuries he said he sustained during the incident, including a bite wound that required antibiotics.
He later reported lingering nerve damage to one finger.
The day after the arrest, on Jan. 17, Mack and Nick met with a disability rights attorney.
According to the declaration, Nick expressed that he wanted to live with Mack and signed a durable power of attorney granting his brother authority over his affairs.
The video of Nick saying he did not want to return to his mother’s home is here:
Nick lived with Mack and his wife from Jan. 16 through Jan. 30, 2025, during which Mack states Nick’s physical condition and stress-related behaviors improved.
During that time, Adult Protective Services opened an investigation and interviewed both Nick and Mack at their home, according to the filing.
On Jan. 30, Issaquah police came to Mack’s home and returned Nick to Danielle.
Mack stated he did not physically prevent Nick from leaving but disputed whether Nick’s wishes were fully considered at the time.
A separate declaration filed by the Mack’s spouse supports his account, stating she personally witnessed multiple incidents in which Nick was struck and appeared distressed, and that Danielle sometimes arrived at their home visibly intoxicated.
The declaration also notes that Nick showed improvements in mood, injuries, and overall well-being while temporarily living with them following the January incident.
Firearms orders and court review
Court orders show Mack was served with a temporary protection order requiring the surrender of firearms. Documents show he surrendered 53 firearms, with his spouse saying he took great care to pack and produce the firearms for law enforcement.
The protection order case remained unresolved at the time of the deaths.
Court records reviewed by KIRO 7 show no final ruling had been made regarding long-term caregiving arrangements, guardianship, or contact restrictions.
Neighbor reaction
“The police came and kicked down their door,” Shelby Rosales, a neighbor of the home where two other bodies were found, said. “They put red tape up and I was like, ‘Oh my god, are my neighbors okay?’”
“They were always kind, considerate neighbors,” Rosales said. “But people have lives that we don’t know about.”
Investigation continues
Police have not said whether the court case directly led to the deaths, and investigators have emphasized that the circumstances surrounding the shootings remain under investigation.
No additional information has been made public.
Anyone experiencing a mental health crisis or concerns about domestic or family violence is encouraged to seek help through local crisis services or by calling 988, the Suicide and Crisis Lifeline.
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