Police say the cases are linked; investigators see no ongoing threat to the public.
MERCER ISLAND, WA — Four people were found dead Tuesday during separate welfare checks at homes on Mercer Island and in Issaquah, about 15 miles apart, after an attorney alerted police to a troubling email. Officers discovered two bodies at each address within roughly an hour, prompting a multi-agency investigation that stretched through the day.
Authorities said the events appear connected, with Mercer Island police investigating a suspected homicide followed by a suicide at the first scene and Issaquah police examining two additional deaths linked to that case. The checks happened late Tuesday morning, Dec. 30. Officials stressed they were not searching for additional suspects and did not believe there was a wider danger. Detectives from both cities worked with King County investigators as they documented rooms, collected firearms and other evidence, and began notifying relatives while waiting for the medical examiner’s formal identifications and rulings.
Mercer Island officers were dispatched about 10:45 a.m. to a residence in the 8400 block of Southeast 46th Street after an attorney representing the homeowner reported receiving a worrying email. When officers arrived, they looked through a window and saw a person who appeared to have a gunshot wound. Police entered and found two people dead inside — a woman in her late 70s and a man in his late 40s — with firearms located in the home. “Both were found with obvious gunshot wounds, and at this point we’re still under investigation as to motive,” Commander Jeff Magnan of the Mercer Island Police Department said. Detectives at that scene identified a potential concern for another individual who had previously lived at the Mercer Island address, prompting a request for a second welfare check in Issaquah.
Issaquah police received the request at 11:37 a.m. and went to a home in the 400 block of Southeast Evans Lane. Officers entered and found a woman in her mid-40s and a man in his mid-30s dead inside, according to police. There were no signs of forced entry. Investigators noted that those two were related to the individuals found on Mercer Island. Officials said the four deaths are being treated as connected incidents but emphasized that the precise sequence of events across the two locations remains under review. No arrests were made, and police said they were not seeking anyone else.
Detectives spent much of Tuesday and into the evening canvassing neighbors and documenting the residences. Evidence technicians photographed rooms and collected firearms on Mercer Island while teams in Issaquah processed the second home and checked electronic communications tied to the initial email that triggered the response. Crime scene tape blocked driveways while officers guided residents around parked patrol cars. By nightfall, officials said the preliminary view of the Mercer Island scene pointed to a homicide followed by a suicide inside the house; investigators did not immediately say who fired the shots or the order of deaths in either city. The King County Medical Examiner’s Office will determine identities and causes of death, and release names once relatives are notified.
Mercer Island, an Eastside city on Lake Washington, rarely reports multiple violent deaths in a single day. Issaquah, a growing city along the I-90 corridor at the base of the Issaquah Alps, has seen sporadic major investigations that often draw regional resources. Tuesday’s response brought in detectives from both departments and coordination with King County agencies. Records show the two addresses are about a 25-minute drive apart, depending on traffic, underscoring the tight timing between the checks. The initial request routed through an attorney suggested a family connection between the homes, and authorities later said the victims at the Issaquah residence were related to the mother and adult son found on Mercer Island, a detail that shaped how investigators secured and processed both scenes.
Officials said the early timeline is anchored by the attorney’s report, the 10:45 a.m. dispatch to the Mercer Island address, and the 11:37 a.m. Issaquah call. Both departments planned to confer with prosecutors once the medical examiner’s findings are in. Detectives will review ballistics, check for gun-purchase records, and examine emails, texts and other digital material recovered from devices to establish the order of events and motive. If the medical examiner confirms a homicide-suicide on Mercer Island, the case there could close without criminal charges; the Issaquah investigation will continue as a death investigation unless new evidence points to a different crime. Officials said any public updates would be posted by the departments as they verify names and next of kin, likely after the holiday schedule.
Neighbors described a heavy police presence on both cul-de-sacs, with officers moving methodically between marked units and evidence vans. Some residents stepped outside briefly as investigators came and went; others watched from windows as the tape stayed up. “It was quiet most of the morning and then suddenly there were police cars up and down the street,” said one nearby homeowner in Issaquah who declined to be named. On Mercer Island, traffic slowed near Southeast 46th Street as patrol cars blocked part of the roadway while investigators worked inside the house. City officials said additional patrols would pass through the areas overnight as a routine measure while detectives continued their work.
As of late Tuesday, police in both cities said there was no indication of an ongoing threat beyond the two homes. The next formal update is expected after the King County Medical Examiner releases identifications and cause-of-death rulings. Investigators said they are still piecing together the exact order of the shootings and who, if anyone, called or messaged relatives before the welfare checks. The case remains active, with evidence processing and interviews continuing into Wednesday.
Author note: Last updated December 31, 2025.