He was this junior protege who debuted in the NRL at 18, who turned 20 the day after Andrew Johns retired and was immediately thrust into the shoes of the future Immortal at the Newcastle Knights before finding himself calling the shots for NSW at the Suncorp Stadium cauldron in Brisbane just a few months later in his only Origin appearance.

That was almost 12 years ago. It must now feel like a lifetime for the former Knights captain.

Not surprisingly, there were periods during his career when he really struggled mentally to deal with the pressures of rugby league. But the pressure of dealing without it has proven to be far worse. Only last week in an interview with his brother Matthew, Johns spoke of feeling completely lost when injury forced him out of the game prematurely back in 2007. Other retirees tell of a similar feeling of emptiness.

For Mullen, that feeling was magnified because when he was rubbed out, he was also ostracized by the game.

His four year ban for using a prohibited drug to treat a chronic hamstring injury meant that not only couldn't he play, he couldn't have any contact with rugby league or the club that had been his life for close to 15 years.

Those close to the former Knights playmaker say he battled big time to come to terms with his sudden "loss" and the feeling that the game had abandoned him.

For months after his banning, there were rumours of financial problems and issues around trying to integrate back into normal life. Then, over the past few days, it became public knowledge that Mullen had suffered a life-threatening drug overdose at his parent's Newcastle home back in December.

READ MORE: Newcastle Knights:

For his family and friends and his former club, it was old news but confirmation from some that he has already come out the other side and is fighting his way back to good health will be welcomed by many in and out of the game who have been left shocked by the extent of his downward spiral. 

Mullen has been linked to a police investigation into a drug supply network allegedly operating in Newcastle and Lake Macquarie but he has not been charged.

In a welcome show of support for him yesterday, Knights boss Phil Gardner claimed the door is not closed on the former captain's return to the club in a mentoring role at some stage in the future once his drugs ban is over. The mood among most Knights fans is there will be encouragement and help out there for him to get his life back on track.

But first, he needs to show he wants to help himself.