NSW Police investigate former NSW Origin representative and Newcastle Knight Jarrod Mullen over alleged drug supply syndicate

Former Newcastle Knights halfback Jarrod Mullen is being investigated by police in relation to an alleged drug supply syndicate in Newcastle and Lake Macquarie.

Mullen, who played 211 games for the Knights since debuting in 2005, and also represented NSW in the 2007 Origin team, is reportedly now linked to an illicit drug supply investigation, headed by Strike Force Castlestead.

The strike force was formed in September 2018 ''to investigate and dismantle an alleged drug supply syndicate operating across the Newcastle City and Lake Macquarie Police Districts,'' a statement from NSW Police said on Monday.

Since December, five search warrants have been executed and 10 people have been arrested and charged in relation to a range of matters including supplying a large commercial quantity of a prohibited drug and knowingly participating in a criminal group. Investigations by the strike force continue and further arrests are anticipated, NSW Police said.

Mullen, who is understood to have left Newcastle, is serving a four-year ban after testing positive for steroids in 2017.

Mullen delivered a positive result for Drostanolone after a routine swab test during pre-season training in 2016.

In March 2017, the Australia Sports Anti-Doping Authority (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.

But he was suspended after the anti-doping tribunal, chaired by former High Court judge Ian Callinan, found in May 2017 that he had violated the game's anti-doping policy.

"As we have said all along, this has been a disappointing matter for all parties,'' Matt Gidley, the then Knights chief executive, said at the time.

''We wish to reiterate this matter took place independently of the club."

He acknowledged Mullen's talent.

''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," he said.