Jarrod Mullen's NRL career is all but over after he was suspended for four years for doping offences.
The governing body on Wednesday rubbed out the former Newcastle and one-time NSW Origin playmaker until 2021 after he was found guilty of taking banned steroid Drostanolone by the NRL's anti-doping body.
The 30-year-old has 21 days to appeal the decision and take the NRL to the Court of Arbitration for Sport.
Mullen delivered a positive result for Drostanolone after a routine swab test during pre-season training last year.
In March ASADA recommended Mullen be banned for four years however he chose not to accept the punishment and appealed to the NRL anti-doping tribunal.
He pleaded for leniency, arguing he was not attempting to gain a competitive advantage but was hoping to repair his body after suffering a second serious hamstring injury in a year.
Mullen, who played 211 games for the Knights since debuting in 2005, was provisionally suspended on January 17 and was on Wednesday suspended after the anti-doping tribunal, chaired by former High Court judge Ian Callinan, found he had violated the game's anti-doping policy.
"As we have said all along, this has been a disappointing matter for all parties," Knights CEO Matt Gidley said.
"We wish to reiterate this matter took place independently of the club.
"It is important to acknowledge Jarrod made a significant contribution to the club over a long period of time and that adds to the disappointment in how he now departs the club."
ASADA CEO Ben McDevitt said: "ASADA will continue to work to protect those athletes who make the right decisions when it comes to injury treatment and rehabilitation"
"Ultimately, Mr Mullen has paid a heavy price for his poor decision making."