The Internet celebrity known as "Kai the Hitchhiker" — accused of beating a 73-year-old Clark man to death — alleges in a letter authorities have repeatedly ignored evidence he was only defending himself from a "drug-facilitated sexual assault."

The letter, posted online by supporters at a Change.org petition calling for "timely advocacy for due process" in Caleb Lawrence McGillvary's case, says the Union County prosecutor's office failed to collect items from the house where the altercation took place, mishandled some of the evidence it did collect, and ignored some of the evidence it had.

Mark Spivey, a spokesman for the prosecutor's office, told New Jersey 101.5 Wednesday the office wouldn't comment on the case. But authorities have acknowledged McGillivary had posted on Facebook claims he was drugged and sexually assaulted.

McGillvary, was arrested at Philadelphia’s Greyhound bus terminal in 2013 after, authorities said, they determined he was a suspect in the murder of 73-year-old lawyer Joseph Galfy of Clark, who was found in his home dead wearing nothing but his underwear and socks when police came to check on him.

Authorities have said McGillvary spent at least two nights in Galfy’s home in Clark, after the two met in Times Square.

McGillvary’s last Facebook post before being arrested asked — in graphic terms —“what would you do?” if you awoke in a stranger’s house and found you’d been drugged and sexually assaulted. One commenter suggests hitting him with a hatchet — and McGillvary’s final comment on the post said “I like your idea.”

That recalled the moment that made him famous — a KMPH news interview in which he described using a hatched to defend a woman against an attacker claiming to be Jesus (seen above).

McGillvary is awaiting trial anticipated to start next year. His full letter is below:

My name is Caleb Lawrence McGillvary and I am a Canadian citizen incarcerated at the Union County Jail in Elizabeth, New Jersey, USA. I have been charged with homicide in an incident where I defended myself against a drug-facilitated sexual assault. During the course of the investigation no rape kit or samples for toxicological analysis were collected from me even though the Prosecutor’s Office knew it was appropriate. They failed to collect many items that could have been used to drug me from the house, or samples from the carpet where they knew the assault occurred. What items that were collected were rinsed with fresh water while testing for fingerprints, without ever once testing for DNA or drug residue. In order to justify these egregious due process violations, the Prosecutor’s Office lied about the purpose of the rape kit performed on the decadent: saying it proved that no signs of being drugged or raped, and that no semen was found. The Prosecutor’s Office also misrepresented the qualifications of a psychologist in order to use the pharmaceutical and forensic medical opinions of this unlicensed “expert doctor” to justify their actions. There was indeed semen found belonging to the decedent, and the opinions of the so called “expert doctor” are inaccurate and intentionally contradict information known to the Prosecutor’s Office from drug enforcement administration training and the UCPO Forensic Laboratory’s use of the American Society of Health System Pharmacists On-Line Database.

Judicial precedents in the New Jersey and United States Supreme Courts hold that part of due process of law is the duty of the Prosecutor’s Office to learn of, collect, preserve, and disclose evidence favorable to the defendant and material to guilt or innocence. The American Bar Association requires that prosecutors not intentionally misstate evidence or mislead the jury as to the inferences it may draw. The UCPO seems to think because I’m an indigent illegal immigrant from Canada, they can violate my procedural rights without consequence. This is an outrage. How can I be expected to prove my innocence when the prosecutor gets rid of any evidence I could use to show I was defending myself from a drug-facilitated sexual assault, and gets away with using expert medical opinions from an unlicensed quack to indict me?

I am in dire straits; and if I don’t receive timely advocacy in this matter to hold those involved accountable to American and international standards for due process of law, I will be lost. Worse yet, the people responsible will be free to promulgate this egregious pattern of injustice upon others. Please respond and let me know that you will do everything in your power to ensure that this matter will end in a fair and just result. Thank you very much.[