The police watchdog is investigating the conduct of officers over the disappearance of a mother-of-three, originally from Teesside.
Rania Alayed, 25, had lived in Norton near Stockton, but moved to Manchester in January. She was reported missing last month.
Her body has not been found but her husband and brother-in-law have been charged with murder.
The Independent Police Complaints Commission is examining how the Greater Manchester force handled information passed on by Cleveland Police.