Not to accuse an innocent man unfairly, of course, but I can understand why cops would want to ask, even from simple curiosity, why a women's severed head was found in this man's suitcase

 Related?

Related?

New York man being questioned by Japanese police about how his date seems to have lost her head. Was it really that good?

A New York man, Yevgeniy Vasilievich Bayraktar,  has been taken into custody in Japan following the discovery by authorities of a severed head inside his luggage, according to reports.
The disembodied head of an unidentified Japanese woman was found inside Yevgeniy Vasilievich Bayraktar’s vacation rental in Osaka Saturday, says local news site Asahi.
The rest of the 27-year-old victim’s body has not been located. Surveillance footage shows Bayrakter venturing in and out of the apartment several times carrying a large bag.
While additional footage shows the woman entering the apartment, she is not seen leaving.
The 26-year-old American tourist has been arrested on charges of “confining a woman.”
He’s denied any wrongdoing.

Well of course he has, bless his heart, and good for him: for the proper retainer, I'll be over there tomorrow to defend him.