MARTINEZ — When investigators entered the home at 243 Escondido Drive in Martinez late last month, they were immediately hit with the smell of death.

Before long, Martinez police had discovered its source, the body of 77-year-old Lyle Lawrence, a retired postal worker, in a bedroom inside the home. He was covered in bed sores, and next to him were “piles and piles” of dried vomit, flies and lice, dried blood and rotting trash, police wrote in court records.

When the initial investigation reached its end, Lyle Lawrence’s daughter, 50-year-old Laura Lawrence, was charged with murder and manslaughter. Laura Lawrence’s boyfriend, 49-year-old Edmund Phillip St. John, was charged with elder abuse. Authorities describe it as a neglect homicide, a rarely applied legal theory that alleges Lawrence’s inattention to her ailing father was so bad it amounted to murder.

Lawrence and St. John were also charged with child abuse, because their 11-year-old son was found in the home. Lawrences also faces a charge of dissuading a witness from reporting the state of the home.

Both defendants pleaded not guilty at an arraignment hearing Monday. Authorities say the child is receiving social services.

It is the county’s first neglect murder case since 2016, when a Concord woman was found guilty of dependent abuse in the death of her paraplegic boyfriend who was suffering from several medical maladies, but jurors hung on the murder count. She later accepted four years in prison in a plea deal.

The home where the two live was empty on Tuesday evening, save for a van and a trailer in the driveway. A sign from the city on a front gate indicated “unsafe conditions” at the home. The front lawn was not mowed and about knee high, but other indications as to the squalor of the house were not present.

According to one neighbor, Lyle Lawrence was a mailman in the neighborhood and well-known for his kind demeanor.

“I just couldn’t believe it when all this came out,” neighborhood resident Virginia Gardner said. “I’ve been here 42 years, and things have always been calm. I would see her once in a while, but they kept to themselves. I didn’t know the boyfriend.”

The investigation into Lyle Lawrence’s death started on Feb. 28, around 10:30 a.m., when police were called to the home for a report of a likely deceased man. Laura Lawrence greeted them, and showed them her father’s bedroom. It was obvious to police that Lyle Lawrence had been dead for days — a suspicion later confirmed by the medical examiner — but Laura Lawrence claimed he had died earlier that day.

“The body was starting to melt into the bedding,” a Martinez detective wrote in court records. “It appeared Lyle hadn’t eaten in weeks.”

When interviewed, Laura Lawrence told detectives that two days earlier, she had found a rat gnawing on her father’s leg, so she trapped it and removed it from the home. She said she regularly brought him food and water, but hadn’t washed him in more than a year, police said.

Lawrence also claimed she did not have the financial means to give her father better care, which she admitted he needed, according to court records. But authorities found evidence Lawrence was accessing her father’s $4,000 per month pension in addition to having a job that paid $30,000 annually, according to court records.

Guns and ammunition were also found in a closet inside the home, and seized by police.