Federal and state investigators have gathered evidence implicating Stephen Dank in wide-scale Medicare fraud and forgery, a development that could see the former Essendon and Cronulla sports scientist face criminal charges and a possible jail term.

Victoria Police detectives and Medicare investigators have interviewed witnesses and obtained documentary evidence that allegedly shows Dank forged and photocopied doctors' signatures to refer patients to pathology clinics in Sydney and Melbourne.

Essendon players are among those whose blood tests may have been ordered as part of the alleged Medicare racket, which may have involved the rorting of tens of thousands of dollars in taxpayer funds.

Fairfax Media can also reveal that AFL club presidents have criticised Essendon chairman Paul Little for his response to the Australian Sports Anti-Doping Authority decision last week to issue show-cause notices to 34 serving and former Bombers players.