Ten months after Essendon doctor Bruce Reid wrote to James Hird to express concern about player injections, the club's medical staff again complained in writing of ''picking up the pieces of something that was running out of control''.

The reference to ''picking up the pieces'' was made by Dr Reid's fellow club doctor Brendan De Morton in an October 2012 email to Essendon's then high-performance boss Dean Robinson, after the doctors learnt the football department was considering billing Medicare for nearly 100 heart diagnostic checks on players that cost almost $10,000.

In an episode yet to be made public, internal emails show that Dr Reid - who on Wednesday had charges over his role in Essendon's supplements program withdrawn by the AFL - and Dr De Morton were unaware of the extent of the heart diagnostic checks and believed that billing Medicare would trigger a fraud investigation.

It is believed the heart checks were done in part to meet AFL player health requirements but also to measure the efficacy of the supplements program.