Security forces were on alert Saturday for possible reprisal attacks after arresting a key leader of the Abu Sayyaf Group accused of kidnapping and beheading several foreigners.
He has been charged with 23 murders, five kidnappings and six attempted murders, a police statement said.
Listed by the United States as a terrorist organization, Abu Sayyaf is a loose network of Islamic militants blamed for the country's worst terror attacks as well as kidnappings of foreign tourists and Christian missionaries.
"The Philippine National Police along with the Armed Forces of the Philippines remain alert and vigilant to prevent and respond to any reprisal attack," PNP spokesman Brigadier General Bernard Banac told AFP.
The AFP said Susukan was behind the April 2016 beheadings of Canadian tourists Robert Hall and John Ridsdel, after Manila and Ottawa rejected the kidnappers' ransom demands.
In 2017 Susukan's group also beheaded Jurgen Kantner, who was abducted from his yacht off the southern Philippines the previous year, said AFP spokesman Brigadier General Edgard Arevalo.
"There is a strong possibility" that Susukan was also behind the 2015 beheading of Malaysian hostage Bernard Then, who was abducted in Malaysia's Sabah state, Arevalo told AFP.
The authorities said Susukan had gone to Davao, near where the Canadians were abducted, to get a prosthetic arm after losing one in a clash with security forces.
Police said they found him in the home of Muslim rebel leader Nur Misuari, who is awaiting trial for an attack carried out by hundreds of his armed followers on the southern city of Zamboanga in 2013 that left more than 200 people dead.
Despite the charges, Misuari has government permission to live at his home and travel.
President Rodrigo Duterte enlisted Misuari's help last year to negotiate peace with various armed groups in the country's troubled south as well as to help negotiate the release of Abu Sayyaf hostages. —Agence France-Presse