(Adds comment from gambler's lawyer)
March 6 (Reuters) - A California man who lost $500,000 in 17 hours gambling at a Las Vegas casino was so drunk he could not remember the episode after waking up in his hotel room, said a lawsuit filed on his behalf that seeks to erase the debt.
Mark Johnston, 52, arrived drunk at the Downtown Grand casino and was plied with free alcoholic drinks while he gambled, according to the suit filed Feb. 18 in Nevada state court for Clark County.
After leaving the gaming tables, Johnston went to his hotel room and woke up the next day with no memory of his time at the tables, stated the lawsuit, depicting his mental state while gambling as a "blackout period."
Johnston's attorney, Sean Lyttle, described him as a self-made millionaire who previously owned a number of car dealerships and was involved in real estate development.
Starting on the night of Jan. 30 and running into the next afternoon at the casino in downtown Las Vegas, a few miles from The Strip, Johnston played pai gow and blackjack for 17 hours and was served about 20 drinks, according to the lawsuit.
Lyttle said he has never heard of a gambler in Las Vegas being allowed to lose such a large amount while intoxicated.
"Mr. Johnston, an experienced gambler, was dropping chips on the floor, confusing chip colors and slurring his speech badly, and he was unable to read his cards or set his hands properly," the lawsuit stated.
The description of Johnston's behavior came largely from Eric Weis, a bartender at the casino who had previously befriended Johnston and sat beside him at one point during the gambling episode, Lyttle said.
Weis has since stopped working at the casino, where he felt pressured by management over the incident, the attorney said.
Before his arrival in Las Vegas, Johnston, a resident of Ventura, had been given credit in the amount of $250,000, and that amount was increased while he was gambling so he ultimately lost $500,000, the lawsuit said.
Nevada gaming regulations prohibit casinos to allow visibly drunk guests to continue to gamble.
A spokeswoman for the Downtown Grand declined to comment on the lawsuit, which accuses the casino negligence, reckless endangerment, fraud and other wrongdoing.
It seeks to have a court declare Johnston's $500,000 gambling debt null and void, as well as unspecified compensatory and punitive damages.
Lyttle said he expects the casino will file a countersuit seeking payment of the debt, after failing to have it withdrawn from Johnston's bank account.
"I'm frankly baffled by the way this was handled and all I can really think to chalk it up to is inexperience," Lyttle said. "This is a casino that opened its doors in November."
(Reporting by Alex Dobuzinskis; Editing by Scott Malone and Gunna Dickson)