The letter that arrived at the State Bar of Georgia in April 2016 containing a white powdery substance contained an ominous threat.

"We will kill of all you. Have some 'anthrax,'" it said, according to federal court records.

Federal authorities said Tuesday that the man who sent that letter, Travis Ball, 50, has been sentenced to two years in federal prison for mailing the threat, which did not contain actual anthrax.

Ball a U.S. Air Force veteran and former state correctional officer sent letters to the bar, The Atlanta Journal-Constitution and the Church of Jesus Christ of Latter-day Saints, threatening harm to their members and employees, prosecutors said.

"Ball's threatening letters, which contained a substance he claimed was anthrax, were meant to instill fear in the recipients and divert critical resources from actual emergencies," said John Horn, U.S. Attorney for the Northern District of Georgia in Atlanta. "We take threats seriously and will use every resource available to protect the citizens of this district."

Ball was an inmate in the Coffee Correctional Facility in Nicholls, Georgia, serving a state prison sentence for arson when he mailed the letters, prosecutors said. The letter to the bar threatened to kill all lawyers. The letter to the Mormon Church in Salt Lake City threatened to kill Mormons and burn their churches, prosecutors said.

In a plea deal with federal prosecutors, Ball pleaded guilty last March to mailing the hoax letter to the bar.

U.S. District Court Judge William Duffey sentenced Ball to two years and ordered him to pay $10,704 in restitution to cover costs incurred by city and county emergency personnel and the FBI after the letters were delivered.

In a sentencing memorandum filed before Ball was sentenced, his attorney, Marcia Shein of Shein & Brandenburg in Decatur, said Ball began "to spiral into mental health decline" that led to his 2013 conviction for arson after he had "experienced difficult situations while serving in the Middle East." She said Ball has suffered for years from post-traumatic stress disorder, depression and extreme anxiety and has a family history of mental illness.

While serving a five-year prison sentence for arson, Shein said Ball "began showing signs of compulsive, disorganized, and threatening behavior in the form of writing letters in other people's names including the letters to the bar, the AJC and the Mormon church, she said. Those letters contained soap and salt flakes, she said. Ball signed them using the names of people he believed "had let him down."

"Though these letters also contained threats to others, Mr. Ball has stated numerous times that the whole purpose was to discredit others, not to harm the recipients," she said.

"From these circumstances, it became readily apparent that Mr. Ball was experiencing a serious mental health collapse."

Shein said psychological and psychiatric evaluations of her client "revealed significant issues that had affected Mr. Ball's downward spiral from an otherwise stable life into mental health decline." Only recently, since Ball's medications have been modified and he is taking them regularly, his symptoms have subsided and the letters stopped. The federal offenses occurred while Ball was not receiving his current medications.

Ball, she added, used his retirement funds and has already paid full restitution to the emergency agencies that responded to the threatening letters.