A man who died in an Atlanta jail cell was "eaten alive by insects and bed bugs", the family's lawyer has alleged.

Lashawn Thompson was jailed on a misdemeanour and placed in the Fulton County Jail psychiatric wing after officials judged him mentally ill.

Family attorney Michael D Harper released photos showing Mr Thompson's body riddled with bugs.

He is calling for a criminal investigation and told reporters a lawsuit is pending.

"Mr Thompson was found dead in a filthy jail cell after being eaten alive by insects and bed bugs," Mr Harper said in a statement. "The jail cell Mr Thompson was housed in was not fit for a diseased animal. He did not deserve this."

According to a Fulton County Medical Examiner's report, Mr Thompson was found unresponsive in his jail cell on 19 September - three months after his arrest - and pronounced dead following attempts by local police and medical personnel to resuscitate him, according to USA Today.

Mr Harper says jail records show detention officers and medical staff noticed Mr Thompson was deteriorating but did nothing to administer aid or otherwise help him, BBC's US media partner CBS News reported.

The medical examiner's report said there was a "severe bed bug infestation" in his cell in the psychiatric ward but said there were no clear signs of trauma on Mr Thompson's body.

The report listed the cause of death as undetermined.

How can bed bugs be deadly?

Photos released by the lawyer paint a morbid picture of Mr Thompson, whose face and torso can be seen covered in bugs.

Conditions of the jail cell as seen in the images are "horrific", said Michael Potter, an entomologist at the University of Kentucky, who specializes in bed bugs.

"I've dealt with bed bugs for 20-plus years," Mr Potter told the BBC. "I've never seen anything quite to this level."

Bed bug bites are not usually deadly, but in some rare cases, Mr Potter said, prolonged exposure to a massive bed bug infestation can cause severe anaemia, which can be lethal if left untreated.

"Bed bugs feed on blood and very large numbers of bed bugs feed on very large amounts of blood," Mr Potter said. In other extreme cases, Mr Potter said, victims may experience an allergic reaction and go into anaphylactic shock, which can also be deadly.

County launches investigation

"It's no secret that the dilapidated and rapidly eroding conditions of the current facility make it incredibly difficult to meet the goal of providing a clean, well-maintained and healthy environment for all inmates and staff," the Fulton County Sheriff's Office said in a statement.

The Office, which runs the jail, has announced a full investigation into the circumstances surrounding Mr Thompson's death. In addition, the statement said, it had made an immediate expenditure of $500,000 "to address the infestation of bed bugs, lice, and other vermin within the Fulton County Jail".

The jail has also updated "protocols for security rounds to include addressing sanitary conditions," according to the statement.

"The ongoing investigation is examining details regarding the medical care provided and ultimately will determine whether any criminal charges are warranted in this case," the statement said.

The Sheriff's Office also reiterated a call for building a new, larger jail to "provide an elite level of care, mental health services, security and cleanliness." County commissioners are studying feasibility plans for a new Fulton County Jail, which has a long reputation of being overpopulated, underfunded, and unsanitary.

Last year, the Southern Center for Human Rights published a press release titled Uncontained Outbreaks of Lice, Scabies Leave People at Fulton Jail Dangerously Malnourished, in which it outlined the many troubles plaguing the facility and offered recommendations to "contain future outbreaks" and improve "hygiene practices".