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.”
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 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.
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, 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, Mack went to the home that morning after a scheduled visit was abruptly canceled.
When he was initially denied access to check on Nick, he called 911.
A physical altercation followed, during which police were summoned.
Officers ultimately arrested Danielle for domestic violence after reviewing the scene and listening to the 911 call, the filing states.
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.
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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