An attorney for a Louisiana inmate allegedly punished for writing letters to a reporter for The Advocate filed a federal lawsuit against more than a dozen current and former state Department of Corrections officials Monday morning, alleging violations of his free speech and due process rights.

William Kissinger, who is serving a life sentence for murder and manslaughter, was abruptly transferred from the Louisiana State Penitentiary at Angola — where he's spent the majority of the past 27 years — to the Elayn Hunt Correctional Center in St. Gabriel due to his correspondence with the reporter who was investigating possible improprieties in the state prison system.

Kissinger began communicating through email and letters with Maya Lau, then a reporter for The Advocate in the midst of a series of stories on Angola, including revelations about financial relationships between former longtime Angola Warden Burl Cain and relatives of prisoners that led to the warden's abrupt retirement in December 2015.

Lau left The Advocate in November and is now a reporter for the Los Angeles Times.

According to the lawsuit, Kissinger — wary of possible retaliation after allegedly being punished decades earlier following a 1995 whistle-blower lawsuit over the relabeling and sale of expired food — alerted prison staff after being contacted by Lau, who initially used an alias in her efforts to contact Kissinger.

After a flurry of email correspondence, which included remarks about goings on in the prison and criticism of prison officials including Cain, Kissinger sent Lau a package of information about alleged financial improprieties at the prison in February, according to the lawsuit. In his messages to the reporter, Kissinger also suggested various avenues of inquiry for the newspaper.

Three days after mailing the package, prison staff informed Kissinger he'd been cited for violating Rule 30-W — "General Prohibited Behavior" — and was abruptly transferred to Elayn Hunt Correctional Center in St. Gabriel, where he spent more than two weeks in a solitary confinement block at the prison, referred to in the lawsuit as "the Dungeon."

During the transfer, the majority of Kissinger's personal possessions — including books, CDs and clothes purchased with money earned over his 27 years in the state prison system — were thrown away, the lawsuit alleges. He was also stripped of his trusty status.

According to the lawsuit, a disciplinary board rejected Kissinger's repeated requests for a copy of the investigative report on the inmate's alleged transgressions, saying prison officials never provided him with documentation of his alleged misbehavior.

Kissinger's appeal of the disciplinary decision was rejected by Elayn Hunt Warden Robert Tanner and Deputy Warden Tim Hooper, who wrote that Kissinger obstructed prison officers and impaired security and stability at Angola. The wardens also said it was "inevident" that Kissinger's disciplinary sentence was retaliatory.

Department of Corrections officials have differing explanations for Kissinger's transfer. An internal email sent to staff at Elayn Hunt and Angola sent on February 4 — the day Kissinger was moved — said Kissinger was being sent to Elayn Hunt “due to protection concerns.” A Department of Corrections subsequently told The Advocate that Kissinger was being punished for breaking two prison rules for which he was eventually cited. In interviews last spring, Corrections Secretary Jimmy LeBlanc suggested Kissinger could have been attacked by inmates loyal to Cain but said he knew of no specific threats to the prisoner's safety.

On Monday, Ken Pastorick, a spokesman for the Department of Corrections, said both are actually the case.

"Mr. Kissinger violated Department policy and was transferred to Elayn Hunt Correctional Center for his protection, and for disciplinary reasons," Pastorick wrote in an email. "Because this matter is in litigation, the Department will not provide any further comment."

In a handwritten letter to The Advocate in May, Kissinger claimed Seth Smith, the No. 2 official at the Department of Corrections and Cain's son-in-law, was orchestrating his punishment and used Hooper — who is the father-in-law of Kristen Hooper, Cain’s granddaughter and Seth Smith’s stepdaughter — to extend his punishment to Elayn Hunt.

Legal scholars have questioned whether prison staff even had a right to read Kissinger's messages with Lau, which Department of Corrections officials have acknowledged were the primary basis for his punishment. In 1978 decision in the case of Guajardo v. Etelle, the 5th U.S. Circuit Court of Appeal ruled that prisoners have “a right to send media mail unopened and to receive media mail that has been opened only for the inspection of contraband in the inmate’s presence.”

Follow Bryn Stole on Twitter, @BrynStole.