Hillsborough disaster: Probe into South Yorkshire police email
A formal complaint has been made against South Yorkshire's chief constable over internal emails relating to the Hillsborough disaster.
David Crompton sent an email in which he said the families' "version of certain events has become 'the truth' even though it isn't".
Police and crime commissioner Shaun Wright said the complaint was made on behalf of "a number of individuals".
An independent investigation will now be carried out.
Mr Wright said: "The request has been submitted by a firm of solicitors in Liverpool acting on behalf of a number of individuals affected by the event.
"This is a formal complaint, which must be dealt with in accordance with statutory procedures.
"I have appointed an independent investigating officer, Chief Constable Simon Parr of Cambridgeshire Constabulary, to investigate the complaint."
'Just be roadkill'
In February, Mr Wright released Mr Crompton's email following a Freedom of Information request.
In September, he had emailed the force's Assistant Chief Constable Andy Holt and head of media Mark Thompson on 8 September, four days before the Hillsborough Independent Panel Report was released.
The email read: "One thing is certain - the Hillsborough Campaign for Justice will be doing their version... in fact their version of certain events has become 'the truth' even though it isn't!!
"I just have the feeling that the media 'machine' favours the families and not us, so we need to be a bit more innovative in our response to have a fighting chance otherwise we will just be roadkill."
In a statement Mr Crompton, who apologised for his comments in February, said: "The Independent Police Complaints Commission (IPCC) looked into the matter at the request of the crime commissioner and publicly concluded that no formal disciplinary proceedings were justified. Nothing has changed since then.
"I had understood the matter to be completely closed but will co-operate fully with any investigation if requested to do so."
The police and crime commissioner's office would not confirm how many emails would be investigated.
South Yorkshire Police's response to the disaster at Sheffield Wednesday's ground in April 1989, which left 96 Liverpool fans dead, is currently subject to a major inquiry by the IPCC.