The man who died inside a Georgia county jail last year had been living in conditions akin to a "torture chamber" before ultimately dying of complications stemming from severe neglect to his mental and physical health, according to the man's family attorneys and an independent medical review.

The independent medical review determined Lashawn Thompson's manner of death at the Fulton County Jail in September 2022 was a homicide, his family attorneys said at a Monday news conference announcing the findings.

The review showed a lack of medication in Thompson's bloodstream, indicating his "severe mental illness" was not being medically treated at the time of his death, attorney Ben Crump said.

"(Thompson) had untreated schizophrenia at the time of his death," Crump said. "There is no question this was criminal negligence."

Thompson, 35, died last year while in custody on a misdemeanor assault charge and was housed in the psychiatric wing of the jail because of his mental health issues, according to family attorney Michael Harper. He had been in custody for just three months when he died in September 2022.

The Fulton County Medical Examiner's office listed Thompson's manner and cause of death as undetermined, according to a document sent to CNN earlier this year. The report listed schizoaffective disorder, bipolar and acute exacerbation as "other conditions."

The independent medical review listed "untreated decompensated schizophrenia" as a contributing cause to the death, in addition to dehydration, malnutrition and severe body insect infestation, which included lice and bed bugs, as "significant conditions."

The review was conducted by Dr. Roger Mitchell Jr., a board-certified forensic pathologist and chair of pathology at Howard University, who was previously the chief medical examiner for Washington, DC, from 2014 to 2021.

Thompson required daily care for his mental illness and noted "a significant gap" of "43 days where there was minimal documentation found within the records that show care being delivered" to him, according to Mitchell's findings.

"For these reasons, it is the opinion of this forensic pathologist that Mr. Lashawn Thompson died due to severe neglect," Mitchell said in the review.

"The combination of dehydration, rapid weight loss, and malnutrition complicated by untreated decompensated schizophrenia led to a fatal cardiac arrythmia of Lashawn Thompson. Had Mr. Thompson received adequate care during his incarceration at the Fulton County Jail then he would not have died at the time that he did," Mitchell said.

When reached for comment, a spokesperson for the Fulton County Sheriff's Office said the agency is working on a statement responding to the review.

Untreated schizophrenia could have contributed, expert says

Dr. Kendall Von Crowns, the chief medical examiner in Tarrant County, Texas, who reviewed and analyzed the report for CNN, said it is too difficult to determine the manner of death based on the independent report.

"I couldn't just knee-jerk call it a homicide just based on what I've seen right now. I would still actually fall on the original report of undetermined," he said.

Von Crowns said without viewing the original autopsy, toxicology report and photos of Thompson's body, "it looks like malnutrition and dehydration is the cause of his death."

In some cases, people with lice infestation can get bacterial infections such as cellulitis or impetigo from scratching their skin, but lice would not have caused Thompson's death, Von Crowns said.

"Based on the limited information we have, it looks more like dehydration or malnutrition, not the lice infestation, because there's nothing in there that's saying that he's had an allergic reaction to the lice, because they aren't saying that there's an allergic reaction occurring. They also aren't saying there's like a massive skin infection, either. So, it's obviously more likely than not his dehydration, malnutrition that caused him to die," he said.

Von Crowns agreed with the independent medical review that Thompson's schizophrenia could have been a contributing factor to his death.

"It would contribute more to that if he's not being properly treated, it would make his underlying mental illness worse and that could also fall into the category of neglect," he said.

Thompson's severe malnutrition and significant dehydration are markers of neglect, as is the condition of the jail cell, but it's not clear from the independent medical review how much his untreated mental illness could have impacted that.

"So, I would agree with there's a degree of neglect as part of this, that he's not put in a clean environment and he's not being taken care of as far as making sure he's eating or kept clean," Von Crowns said, adding that in some cases, people with schizophrenia can cause self-neglect if they refuse to eat or drink.

The degree of neglect ultimately plays a big role in determining the manner of Thompson's death.

"Usually if the neglect is caused by a caretaker and other individual caring for them, it would fall into the category of homicide if the caretaker knows they are willfully and wantonly withholding care to this individual that would put it in the area of homicide," Von Crowns said.

Thompson was living in 'inexcusable' conditions, attorney says

During a news conference in April, the family and attorneys held up photos that purportedly showed conditions inside Thompson's jail cell.

"The cell he was in was not fit for a diseased animal. This is inexcusable and it's deplorable," attorney Harper said at the time.

Thompson's family has repeatedly demanded a criminal investigation into his death and for the facility to be closed and a new one to be built.

On Monday, NAACP Georgia Chapter President Gerald Griggs said criminal negligence charges should be filed against anyone connected to Thompson's death. Griggs called on Gov. Brian Kemp for more mental health funding for the state.

"(Thompson) was innocent, he was merely being detained. That should not have led to his death," Griggs said.

After Thompson's death, the Fulton County Jail's chief jailer and two assistant chief jailers resigned at the request of the county's sheriff, according to a statement from the sheriff's office, which did not name them.

The sheriff's office also allotted a $500,000 emergency expense "to address the infestation of bed bugs, lice and other vermin" within the jail, the agency said last month.

A process to transfer more than 600 inmates to other counties "in an effort to help relieve overcrowding, at an average cost of approximately $40K/day," had also begun, the sheriff's office said last month.