David Parkin has revealed he sacked staff during his AFL coaching career over fears they were giving players illegal substances.

As the investigation into claims Essendon players were administered performance-enhancing drugs continues, with lawyers on Monday indicating players were unlikely to be interviewed by the Australian Sports Anti-Doping Authority until late next month, Parkin has suggested drugs have been a long-time issue.

The four-time premiership coach began in the VFL-AFL at Hawthorn in 1977, spent time at Fitzroy and had two stints at Carlton, finishing with the Blues in 2000.

”You could employ someone who for fame or fortune reasons becomes the rogue operator, if you like, within your organisation,” Parkin said. ”I have been down that path, where we have got rid of people who have serviced the needs of players that I did know about – we changed them because they were not doing the job the way we expected them to do.”

Asked whether that had meant a staff member had been trying to give illegal substances to players, Parkin replied: ”Um – I am not really sure but there was some evidence to suggest that might be so and we weren’t prepared to take a risk that there might be somebody in the place that wasn’t operating all above board.”

Parkin spoke as a panellist on SBS television’s Insight, airing on Tuesday night. He was then asked by journalist Jenny Brockie whether that had meant he had ”smelt a rat”.

”No, it’s a vague thing, because of my position, and I am responsible, you can’t allow that, Jenny, to develop,” he said.

Parkin did not specify at which club or clubs he had sacked staff. He did not return calls on Monday.

Seated alongside former Essendon vice-captain Andrew Welsh and Port Adelaide sports scientist Darren Burgess, Parkin said sports scientists have become increasingly influential in clubs and felt the pressure on coaches to get an edge over competitors led to the temptation to bend the rules.

Parkin is the president of the AFL Coaches Association and understands what pressures the modern coach faces.

ASADA interviews of Essendon coaches and staff continue to be conducted, with lawyers confirming players’ interviews are to follow and are unlikely to be completed until May.

This, according to lawyers, means a final report is unlikely to be completed until the end of the AFL season, if not into October.

Welsh, who retired after the 2011 campaign, before controversial sports scientist Stephen Dank joined the Bombers, said the players had put their trust in the club.

”There [have] been supplements from when I was playing, they are a lot more advanced now, and the way they are taking them,” he said. ”But there were no players that raised any concerns when I spoke to them about it because you do put the trust in the club.”

The original release of this article first appeared on the website of Hangzhou Night Net.