A man accused of bashing Assistant Police Commissioner Chris O’Neill appears to have made hundreds of posts on social media while in prison, including explicit threats against other Facebook users.

The prolific use of Jay Stephens' Facebook account raises serious concerns about prisoner access to social media while on remand and the potential to interfere with the administration of justice.

Contacted by The Age on Sunday, the Department of Justice and Community Safety confirmed the Facebook posts would be investigated.

Jay (left) and Isaiah Stephens in an image taken from CCTV footage released by police. Credit:Victoria Police

Mr Stephens, 20, and his brother Isaiah Stephens, 18, were both charged with serious assault offences over the alleged attack on Mr O'Neill at St Kevin's College in Toorak on June 15.