A review of rape investigations in London has been called by the Metropolitan Police Commissioner amid concern about varying clear-up rates.
One in five reported rapes in London leads to caution or charges
Overall, about one in five reported rapes in London leads to a caution or charge, but rates vary widely between and within boroughs.
The inquiry will examine what factors are causing such differences to exist.
The review, to be led by Deputy Assistant Commissioner Brian Paddick, will report back within two months.
It will investigate whether variations in clear-up rates can be explained by the number and skill of officers involved in the cases, or if other factors are to blame.
Mr Paddick told BBC Radio 4 there were "widely differing rates of crimes being solved" within boroughs.
"It is something more than simply the number of officers or the calibre of officers that are being employed - there are other factors at work here and that is what we are trying to discover by having this review."
The review will also examine rape allegations where no further action is taken, classified by police as "no crime", to make sure genuine offences are not being overlooked.
Although the inquiry is not due to report back for two months, Mr Paddick said it had already been decided that each London borough would have its own dedicated rape investigation unit.
Detection and clear-up rates for rape offences nationally have caused concern for some time.
A Home Office study published in February found the percentage of reported rapes leading to convictions in England and Wales had fallen to an all-time low.
The report, carried out at London Metropolitan University, said the number of reported rapes reported was rising - but only 5.6% of 11,766 reports in 2002 led to a rapist being convicted.
Last summer, the Crown Prosecution Service launched new rules on the handling of cases, after Home Office figures revealed wide variations in conviction rates across England and Wales.