Fatal Delusion (1995)

Deranged Vietnam vet David Kates suffers from flashbacks of the atrocities he endured during the war; savagely murdering and mutilating innocent brunette women who resemble the enemy Major who tortured his brigade. Shortly after being captured and imprisoned for his crimes, Kates escapes from prison, murders his vacationing jailhouse shrink, and assumes his identity. Now masquerading as a psychologist, Kates infiltrates the police department and offers his assistance in helping to capture the escaped serial killer who's dismembering local women. Unfortunately for the police, the doctor they're collaborating with is the actual lunatic they're in search of...and his delusion means death for everyone.