The Georgia family claims poor prison conditions and insect bites contributed to the inmate's death

(CNN) The family of Lashawn Thompson, an inmate who died in the Fulton County Jail last year, is calling for a criminal investigation into his death and for the facility to be closed and a new one built.

At a news conference Thursday, family attorney Michael Harper blamed unsanitary conditions and complications from insect bites for Thompson's death in September after three months in custody.

Holding up photos purportedly showing the conditions in Thompson's prison cell, Harper said: “The cell he was in was not fit for a sick animal. This is inexcusable and regrettable.”

The Fulton County Sheriff's Office said in a statement that the law prohibits the department from releasing information about Thompson's medical condition at the time of his incarceration, “or what decisions he made regarding his right to accept or refuse medical care.”

According to a document sent to CNN, the Fulton County coroner's office said the manner and cause of death were undetermined. The report listed schizoaffective disorder, bipolar disorder and acute exacerbations as “other disorders.”

According to Harper, Thompson had been incarcerated for assault since June 2022 and was admitted to the prison's psychiatric ward because of his mental health issues.

Brad McCrae, Thompson's brother, told reporters his brother “didn't deserve this.”

Thompson, 35, was from Winter Haven, Florida, but loved Atlanta and commuted between the two cities. McCrae said his brother enjoys listening to music and cooking.

Asked by a reporter what he thought when he saw images of his brother's body and the conditions in his cell, McCrae said: “It was heartbreaking because no one should be seen like that.” No one should see that. But the first thing that came to mind was Emmett Till.”

The sheriff's statement acknowledged the “dilapidated and rapidly deteriorating conditions” at the jail and said Fulton County Sheriff Patrick Labat also wants a new jail.

“Without making any specific statements regarding Mr. Thompson's medical condition, it is fair to say that this is one of many cases that illustrate the urgent need for expanded and improved mental health services,” the office's statement said. “This is precisely why Sheriff Labat continues to call for the construction of a new jail and criminal justice complex in Fulton County.”

CNN's Steve Almasy contributed to this report.