Selected for a routine random drugs test after a Newcastle Knights' pre-season training session, Mullen provided a sample in which ASADA subsequently detected traces of drostanolone, a banned steroid.

The positive swab was not publicly revealed for almost two months, at which point the former NSW Origin playmaker was immediately stood down. His pleas for leniency at the ensuing drugs tribunal hearing - where he claimed he had been prescribed what he believed was an amino acid to treat a chronic hamstring injury - fell on deaf ears.

He was handed the maximum suspension of four years, and at the age of 30 his rugby league career was effectively over.

Some will have no sympathy and say he should have known better, especially given the anti-doping education that professional athletes receive on a regular basis.

But those who know him, myself included, will be more inclined to reflect on the devastating impact this must have had on a decent bloke whose life's work had been ruined by one silly mistake.

Mullo was born to be a footballer. His dad, Steve, played first grade for Canterbury and Wests and Jarrod's earliest memories are of being a ball boy during Steve's days as captain-coach at Singleton. He was a Year 12 student in the library at St Francis Xavier, Hamilton, when he fielded a call from Knights coach Michael Hagan in 2005, informing him he would be making his NRL debut that weekend, at the age of 18.

Over the next 12 seasons, he would appear in 211 top-grade games, one Origin, and captain the Knights to two victories in the 2013 play-off series. If not for his suspension, he was on track to become the club's most-capped player.

Suddenly all this was snatched away from him, and as his mother, Leann, explained in an emotional interview with ABC radio months later, her son was "in deep despair", adding: "Jarrod's dedicated himself to the Knights for 12 years ... it's very disappointing that, I feel, that support hasn't been forthcoming."

Mullen is far from the first elite athlete to struggle once his or her career reaches full-time. As another former schoolboy NRL prodigy, Brett Finch, said recently: "One day I was a football player, the next day no one cares. It's over. I struggled to get any satisfaction ... I was trying to get some highs in my life."

In Finch's case, he had at least retired of his own volition, at the age of 32.

In contrast, Mullen's playing days ended effective immediately, and the two years he had to run on the most lucrative contract of his career were terminated.

With the benefit of hindsight, is it any real wonder Mullen's life has since spiralled in the wrong direction?

I had my concerns midway through 2016, before he tested positive, when I noticed Mullen outside the Honeysuckle restaurant he partly owned, sharing a coffee with Les Mason, brother of his former Knights teammate Willie.

The following year, after Mullen had been banned, he arrived at Newcastle Local Court in a show of solidarity as Les appeared for sentencing, having pleaded guilty to supplying 58 grams of cocaine.

Most expected Les to be jailed. Instead he was placed on a two-year intensive corrections order, an alternative to a full-time custodial sentence.

Within 12 months, detectives started monitoring Les and other members of an alleged drug syndicate, which also included Mullen.

Les was arrested and earlier this year pleaded guilty to supplying a commercial quantity of Butanediol - an industrial solvent that is used as an alternative to party drug Gamma-Hydroxybutyrate (GHB). The charge carries a maximum of life imprisonment.

Mullen, meanwhile, reportedly suffered a near-fatal drug overdose last December and then spent six weeks in a rehabilitation centre.

He had not long been released when he was arrested and charged with supplying cocaine on four occasions at Cameron Park during November last year.

After initially indicating, in June, that Mullen would defend the charges, his lawyer told Newcastle Local Court on Wednesday that his client would plead guilty to one charge of supplying cocaine. The other three counts were withdrawn.

Mullen will be back in court on December 4.

It's a sad story and, while I'm sure Jarrod would be the first to admit he has nobody to blame but himself, there have been extenuating circumstances.

As an impressionable teenager, he was playing first grade for a club that has been involved in more than its fair share of drugs scandals - both social and performance-enhancing.

Then the pressure he felt while sidelined after hamstring surgery in 2016 prompted him to take a career-ending gamble.

A young man who had lived his whole adult life inside the professional rugby league "bubble" was cast aside into the real world, and sadly went off the rails.

Does that make him a bad person? Not as far as I'm concerned.