The suspect in the stabbing of main opposition Democratic Party(DP) leader Lee Jae-myung in Busan on Tuesday had arrived in the port city a day earlier.

According to the Busan Metropolitan Police, who grilled the man in his 60s surnamed Kim until around 12 a.m. Wednesday, he had traveled alone from South Chungcheong Province via the KTX bullet train Monday morning.

Police said Kim had spent the night in the nearby city of Ulsan before returning to Busan on Tuesday to commit the attack with a partially modified 17 centimeters long hiking knife .

While the suspect has testified that he had acted alone, the police began a raid of his South Chungcheong residence and office as well as a search of his mobile phone for evidence suggesting that he had planned the attack in advance.

The police are also in the process of verifying Kim's membership in any of the nation's political parties.

The police and the prosecution are expected to seek the pretrial detention for the suspect on attempted murder charges as early as Wednesday.