The former national head of counter terrorism is to oversee an inquiry into 25 Birmingham schools over allegations of a hard-line Islamist takeover plot.
Peter Clarke, the ex-deputy assistant commissioner of the Met Police, has been appointed by the Department for Education (DfE) to review the evidence.
Birmingham City Council said it had more than 200 reports over its inquiry.
West Midlands Police Chief Constable, Chris Sims, said it was "a desperately unfortunate appointment".
He added: "Peter Clarke has many qualities but people will inevitably draw unwarranted conclusions from his former role as National Co-ordinator for Counter Terrorism."
Anonymous claims were made in a letter sent to local authorities last year.
The so-called "Operation Trojan Horse" letter was apparently written by someone in Birmingham to a contact in Bradford.
Mr Clarke, who has been appointed as education commissioner, is due to report back with his findings in the summer and his remit will cover local council-run primary and secondary schools as well as academies.
Explaining the appointment, Education Secretary Michael Gove said: "I have already asked Ofsted to inspect a number of schools of concern and these investigations are ongoing.
The DfE said Peter Clarke would work closely with the city council
"But wider, more comprehensive action is needed.
"These allegations need either to be substantiated and firm action taken, or to be shown to be baseless.
"We cannot allow uncertainty for parents or pupils to persist."
The DfE said Mr Clarke would be responsible for analysing "evidence of extremist infiltration in both academies and council-run schools".
It added he has substantial experience in leading high-level investigations and his appointment meant the allegations could be examined in a "professional and dispassionate manner".
The department said Mr Clarke would work closely with the city council, which has appointed former head teacher Ian Kershaw as its own chief advisor.
The council's investigation, running in parallel to the DfE's inquiry, is due to initially report back in May.
In his statement, Mr Sims added: "I am a strong supporter of open and inclusive education for all children in Birmingham and across the West Midlands and am committed to the process adopted by Birmingham City Council with educational and social inclusion at its heart."