THE AFL is confident the investigation into Essendon's supplements scandal will be resolved well before the finals series.

One of the nightmare scenarios for the League is that the Australian Sports Anti-Doping Authority (ASADA) hands down its findings during the finals, with Essendon still in premiership contention.

But AFL deputy chief Gillon McLachlan said on Sunday that was unlikely to happen.

"I'm hopeful and optimistic it's somewhere in the first half of August," he told Channel Seven's Game Day.

"This issue has to be brought to a head before the finals.

"I believe that ... I have a good line of sight on it, I believe with some degree of confidence that will be done."

But McLachlan also admitted the timeframe of the ASADA investigation so far had been a "moveable feast".

The AFL and ASADA have conducted parallel investigations into the use of supplements at Essendon last season.

The two bodies have maintained close contact over the issue.

The anti-doping body will announce its findings and then the League will hand down its verdict.

Regardless of whether ASADA finds Essendon breached the anti-doping code, the Bombers could face heavy sanctions from the AFL for the damage the saga has done to the game's image.

ASADA and AFL officials continue to conduct interviews with Essendon players, coaches and other staff over last year's controversial supplements program.

The Age reported on Sunday that assistant coach Mark Thompson will front investigators early next month.

Thompson is a key figure in the saga, having helped bring high-performance manager Dean Robinson to Essendon from Geelong.

Robinson then worked with sports scientist Stephen Dank, who ran the supplements program.

Dank is no longer at the club and Robinson is serving a long-term suspension.

Essendon has already conducted an independent review of club operations and governance as a result of the crisis.

Bombers chief executive Ian Robson resigned in May after first offering to do so in February, when news broke of the scandal.