Police in Sapporo said Sunday they have begun questioning a woman in her 50s over a series of gas cylinder explosions in the city’s Kita Ward this year.
Since January, there have been five mysterious explosions of gas cylinders filled with nails and thumb tacks at police stations and a commercial facility within a 3-km radius of a police station in Kita Ward. In the most recent blast on April 3, a gas cylinder filled with nails exploded at a police dorm, but no one was injured.
Police said the gas cylinders are the type commonly used in portable stoves.
Since the first attack, police said four letters, all of which have contents alluding to the series of crimes, were left at both the Kita Ward police station and at the office of a local news agency.
TBS reported that police identified the woman through surveillance camera footage and on Saturday searched her apartment.
The woman has denied any involvement in the explosions.