Tamisha Marie Mendenhall, 34, was found dead alongside her husband, 54-year-old Jeffrey, and their youngsters, six-year-old Thomas and three-year-old Olivia, inside their Michigan home on Thursday night time.
State police described a bizarre scene inside the home where a mother is suspected of killing her two young children and husband –including finding a rented helium tank, plastic bags with tape on them, and sleep-inducing medication.
The bodies of the children, ages 6 and 3, were found next to each other in a bedroom, arranged in a peaceful pose, holding stuffed animals and flowers.
Their father's body was found on the floor of a hallway with his head resting on a pillow. He, too, was holding flowers.
The victims are Jeffrey Mendenhall, 54, and his children, Thomas, 6, and Olivia, 3. None of them suffered physical injuries.
Unlike the others, the body of Tamisha Marie Mendenhall, 34, was found in a "significant" pool of blood near her husband. An autopsy later revealed she had a self-inflicted stab wound to the groin that pierced her femoral artery.
Police say evidence shows Tamisha Mendenhall was the last one alive in the home.
Police believe all of the deaths occurred Tuesday afternoon, Aug. 11, in their mobile home in Garfield Township, just outside of Traverse City.
Their bodies were discovered late Thursday after Jeffrey Mendenhall failed to show up for work at Munson Medical Center for two days.
Prosecutors last week said investigators believed that Tamisha Mendenhall orchestrated the killing of her family.
Police did not specify exactly how Mendenhall's husband and children died but provided details of what they found at the crime scene.
Investigators said they found "numerous empty prescription medication bottles, some dated Aug. 11, 2015, of medications comprised of Benzodiazepine, a medication generally prescribed to treat anxiety and induce sleep."
"Some of the prescription medication capsules had been opened. White residue was discovered on a couple of small medical cups.
"Also discovered inside the home was a helium tank that was in the bedroom where Thomas and Olivia were discovered and just a couple feet away from where Jeffrey's head lay."
Also found were empty kitchen trash bags with tape on them, vinyl tubing and a valve for the helium tank, which was found in the kitchen. Someone had modified the tanks valve so that it would attach to the tubing, police said.
Toxicology results are pending on the family.
Police found a brief note, believed written by the father, that "mentioned the children were innocent," Michigan State Police Lt. Kip Belcher told The Grand Rapids Press and MLive on Monday, Aug. 17.
A prosecutor last week said it appeared the mother, Tamisha Mendenhall, 34, was responsible.
"There's absolutely no conclusion at this point that the mother was the sole responsible individual for committing the homicides of the two young children," Belcher said.
"We certainly cannot eliminate Jeff as being a participant."
The children, Thomas, 6, and Olivia, 3, were found near each other in a bedroom, holding stuffed animals and flowers in their arms. Their father was found in the bedroom doorway, his head resting on a pillow. He was holding flowers, too.
The mother died of a self-inflicted stab to her groin that pierced her femoral artery. She quickly bled to death. Her blood pooled beneath her husband.
Police have concluded she was the last to die.
Police found empty kitchen trash bags with plastic tape on them, vinyl tubing and a valve for a helium tank in the trash container in the kitchen. The valve had been modified with tape so it could be attached to vinyl tubing.
The use of helium is considered by some to be a relatively painless way to commit suicide because it does not cause a feeling of asphyxiation, Dr. Stephen Cohle, a forensic pathologist, told The Press and MLive.
Cohle, who is not involved in the investigation, said simply opening a helium canister likely would not cause harm, but breathing it in a closed plastic bag could be deadly. He is aware of helium being used to commit suicide in West Michigan.
"It's a fairly efficient way to die," Cohle said.
Many know about using helium based on Derek Humphry's book, 'Final Exit," about euthanasia, he said.
"This is one of the ways suggested by Mr. Humphry," he said.
Police think the deaths occurred Tuesday, Aug. 11, at the family's home at Town & Country Mobile Village, just outside of Traverse City.
On Thursday, state police, conducting a welfare check after the husband failed to show up for work, found the bodies.
The children were posed together inside a bedroom. Their father was partially in the hallway. His body did not show any signs of a struggle, leading police to suspect he committed suicide. Police have not yet been able to determine if one or both parents played a role in the children's deaths.
Police have determined the mother was the last one alive, and she killed herself.
"There are some questions we may never have the answer for," Belcher said. "There's no explanation for why."