A zoo worker in northern Japan has been arrested on suspicion of disposing of his wife’s body in an incinerator at the facility.

Suzuki Tatsuya, 33, an employee at the popular Asahiyama Zoo in Asahikawa, was arrested after investigators found what appeared to be human remains in an incinerator for disposing of animal carcasses.

Authorities alleged the remains belonged to his wife, identified only as Yui, 33. They said Tatsuya burned the body around 31 March.

The investigation began after a relative reported the woman missing in April.

Police said the suspect had earlier threatened his wife saying he would burn her until nothing remained, according to The Japan Times. “It’s true,” he reportedly told police during his interrogation.

The investigation delayed the zoo’s opening by a few days for the summer season. It had been closed for maintenance on 8 April and was scheduled to open on 29 April. Since the investigation was ongoing, the zoo was finally thrown open to the public on 1 May.

Authorities say the investigation is ongoing. The motive is yet to be ascertained.

City officials described the case as deeply unsettling.

Mayor Hirosuke Imazu called it an “unprecedented crisis.” “No one could have predicted it,” he said. “I am overcome with immense anxiety, and I am facing a crisis of unprecedented magnitude.”

“We deeply apologise for causing great concern and inconvenience,” Mr Imazu said after the man was arrested. “We will continue to fully cooperate with the investigation.”

In spite of the incident, local reports suggested that there was a long queue outside the gates as the zoo opened on Friday morning. Several visitors said they had been following updates closely and decided to proceed with their plans.

“It is sad that the actions of a single person could tarnish the impression of the entire zoo,” an unnamed visitor told The Asahi Shimbun paper. “I hope it keeps doing its best just as before and welcomes animal lovers like me.”

One visitor noted the animals had done nothing wrong while another described the zoo as a lasting symbol of the city.

Officials apologised to visitors but said they hoped to move forward.

The zoo said it received several hundred messages from the public. “Asahiyama Zoo is a treasure of Asahikawa,” one said. Another wrote an encouraging message for the zoo staff: “For the sake of the animals, I hope all of you will get through this together.”

Acknowledging messages of support, the mayor said: “Drawing strength from the encouragement we have received, we will continue, as we always have, to firmly convey the vibrancy of the animals’ lives.”

Asahiyama Zoo, opened in 1967, attracts over a million visitors a year. It is known for its distinctive enclosures, such as glass domes and overhead cages, which lets visitors view animals from up close.