A man caught on surveillance cameras after an explosion outside a public restroom at Tokyo’s Yasukuni Shrine on the morning of Nov. 23 is South Korean and has already flown back to his country, investigative sources said Thursday.

The man entered Japan just a few days before the incident and left on the day of the explosion, the sources said.

Security cameras around the restroom captured a man in dark clothes wearing glasses and carrying a backpack and a bag approximately 30 minutes before the blast at the shrine, which is viewed as a symbol of Japan’s militarist past in China and South Korea.

The Metropolitan Police Department has been attempting to track the man’s movements by analyzing video footage and examining whether the man is linked to the explosion, which caused no injuries.

The sources said items found in one of the toilet stalls of the restroom bore Korean Hangul writing.

According to the sources, the man was seen heading toward the restroom, where the blast occurred. Subsequent footage from the shrine showed him without the bag, exiting the compound by the nearby South Gate and walking toward Kudanshita Station.

The MPD also checked videos from security cameras in the neighborhood of the shrine in Chiyoda Ward and found that the man did not use the station but walked to a hotel in the same ward, the sources said, adding that the police determined that the man then left for South Korea.

South Korea would consider handling the case based on “law and procedures” if Japan were to ask that the suspect be handed over, South Korea’s Foreign Ministry spokesman said Thursday.

“At the moment, it’s our understanding the suspect has not been specified,” Cho Joon-hyeok said during a news briefing. He also said the Japanese government had not informed South Korea of the outcome of investigations, nor asked for cooperation on the case.

The blast was heard at around 10 a.m. About 100 people were visiting the main hall for a religious festival that had just started. It came at a time when police stepped up their vigilance in the capital following the terror attacks in Paris 10 days earlier.

The ceiling of the stall in the men’s restroom had a square hole measuring about 30 cm on each side and a bundle of four metal pipes was also found in the ceiling, the sources said. The pipes contained a granular substance presumed to be gunpowder, with three of them nearly emptied apparently after combustion occurred, they said.

On the floor of the stall was a digital timer with a wire lead attached to a battery case, the sources said. Batteries were also found scattered about.

The MPD suspects the apparent handmade explosive fizzled and the police are studying the device and the substance.

The shrine is the source of diplomatic outrage from China and South Korea whenever high-ranking Japanese politicians pay homage there, after it added Class-A war criminals to its honor list in the late 1970s along with around 2.5 million war dead.

It has been targeted for attacks in the past, including a suspected arson by a Chinese man who allegedly poured gasoline on a gate post at the shrine in December 2011. In December last year, a Japanese man was arrested after an attempted self-immolation on the shrine’s premises.