Tatsuya Ichikawa, a forensics specialist, was in a fast food restaurant in Shizuoka Prefecture, central Japan.
He was then spotted licking a 25-year-old woman's hair before police were called and Ichikawa was detained, according to Agence France-Presse
The police department where Ichikawa worked said that he was on medical leave and did not specialise in human hair.
Ichikawa is reported to have told police: "I wanted to lick so I did."
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