ASADA has re-interviewed key witnesses in the Essendon investigation in recent weeks, as the anti-doping body seeks to shore up evidence before taking any potential action against Essendon players.

ASADA has  questioned those involved in the supply of peptides to the club within the last seven to eight  weeks – in an attempt to ‘‘tighten up’’ the evidence before proceeding further with any show-cause notices.

Inquiries have been made overseas to try and establish a chain of evidence from the peptide source in China, through the Australian distributor to the Essendon players. 

Fairfax Media understands that the investigators have been in contact with key witness Shane Charter, who supplied peptides to ex-Essendon sports scientist Stephen Dank, and ASADA is also believed to have been in contact with compound chemist Nima Alavi, and potentially others.

ASADA was instructed to seek clarifications on pivotal information after a review of existing evidence by former Federal Court judge Garry Downes.

ASADA wanted more precise information about how certain substances were sourced, where they were sent and at what time, with a focus on the passage of Thymosin beta 4 from China to the club. 

Charter had already told ASADA that he purchased a batch of banned peptide Thymosin beta 4 in China, along with other substances, at the behest of Dank, and gave instructions on how to use TB4 to Dank.

Essendon has long maintained that it did not use the banned version of Thymosin, backing Dank’s claims – which ASADA hasn’t formally heard because he has refused to co-operate – that he gave the players Thymodulin, a substance that isn’t banned.

Consent forms devised by Dank and signed by Essendon players said only ‘‘Thyomsin’’ without specifying what type. There is no suggestion that the club ever had possession of Thymosin Alpha,  a legal variant that has been used for AIDS patients.

Most recent speculation about imminent show-cause notices has centred on TB4, rather than the peptide AOD-9604, which the World Anti-Doping Agency has deemed banned under the S0 category of the WADA code (not approved for use), but which Essendon contended was not known to be banned during 2012. 

If the players receive show-cause notices, they have 10 days to respond – and to say why they should not be listed on the ‘‘register of findings’’ of a possible anti-doping rule violation. If the player could not persuade the anti-doping rule violation panel otherwise, infraction notices would be issued by the AFL, with the player facing an AFL tribunal.

 Players or officials could legally challenge their placement on the register of findings in the federal administrative appeals tribunal. If the player doesn’t take legal action, he can appeal in the AFL appeals board. ASADA’s new boss Ben McDevitt has said the Essendon case will be finalised in weeks, not months.