Two police forces are to set-up a joint unit to investigate serious crimes such as murders, rapes and kidnappings.
Cleveland Police and North Yorkshire Police will launch the Major Investigation Team in November.
Both forces have denied the merger is a cost-cutting measure.
North Yorkshire Assistant Chief Constable Ken McIntosh said it was "about putting in an investment into the teams."
As well as dealing with new crimes the unit will also investigate cold cases and take over ongoing inquiries, such as the hunt for missing York woman Claudia Lawrence.
'Low crime rate'
Mike Stubbs from North Yorkshire's Police Federation, which represents junior police officers, said the merger could help in the initial stages of an investigation by allowing "resources to be put into place more quickly".
However, he added that the federation had concerns over the different crime rates in the two counties.
"We are one of the safest and we have a low crime rate," he said.
"Cleveland can't make that same claim.
"So our concern is that because of the higher demand in Cleveland the resources that North Yorkshire Police are committing to this collaboration may be drawn into investigating crimes in Cleveland not in North Yorkshire."
The forces are also planning to combined their dog units with Durham Constabulary, in an effort to save by £3m over five years.