A man managed to fatally stab a woman on Monday in Fukuoka City, southwestern Japan, despite the police knowing he was stalking her.
Terauchi Susumu, a 31-year-old resident of Fukuoka City, was arrested on Wednesday.
Investigators suspect Terauchi fatally stabbed his 38-year-old former girlfriend Kawano Miki on a street near JR Hakata Station on Monday.
Police say Terauchi had been in a relationship with Kawano for about six months.
On October 21, Kawano had contacted the police saying she wanted to break up with Terauchi but he had taken her mobile phone. She requested their assistance in getting it back.
Three days later, Kawano told the police she got her phone back, but said Terauchi refused to break up.
In text messages to Kawano confirmed by the police, Terauchi said he considered them to be a couple and that he wouldn't forgive her if she got angry.
The police advised Kawano to move to a safe place and change her job. They also questioned Terauchi and issued a warning to him to stop contacting her.
Initially he appeared to comply. But about a month later, Kawano told the police Terauchi had come to her workplace. She asked them to issue a new warning.
Two days later, she told the police Terauchi had tried to call her three times. When she didn't answer, he called her workplace.
On November 26, the police decided the matter was of high urgency and ordered Terauchi to stay away from Kawano.
The police began to regularly patrol the area around Kawano's home and gave her and her family devices to instantly contact them. Last month, the police stepped up their patrols.
A senior official of the Fukuoka prefectural police told reporters on Wednesday that the measures taken by the police had been appropriate and it was extremely regretful the victim died.