MELBOURNE, Australia (AP) — Australian police say they have arrested one of three men they suspect are responsible for an arson attack on a Melbourne synagogue that marked a major escalation in antisemitic violence across the nation.

A 21-year-old Melbourne man was arrested at a house on Wednesday on suspicion that he had set fire to the Adass Israel Synagogue in December, Victoria Police Deputy Commissioner Wendy Steendam said. The predawn attack destroyed the synagogue and left a worshipper with minor burns.

The arrest is a major breakthrough for investigators in the Victorian Joint Counter-Terrorism Team that is treating the attack as politically motivated.

The team involves Victoria state and federal police as well as Australia’s main domestic spy agency. More than 220 law enforcement officers have devoted more than 50,000 hours to the investigation.

The suspect, who has not been named, was being questioned on Wednesday about offenses including arson, conduct endangering life and car theft, Steendam said.

An arson conviction carries a potential maximum of 15 years in prison, while the other two offenses are each punishable by 10 years imprisonment. The suspect has yet to be charged.

“This investigation remains ongoing and we anticipate there’ll be further arrests,” Steendam told reporters.

“I want to reassure Victorians, particularly those in the Jewish community, that we remain relentless in our pursuit in finding all those responsible for this crime and holding them to account,” she added.

Police suspect international criminal links

Police suspect offshore criminals had worked with associates in Victoria to orchestrate the attack, Australian Federal Police Deputy Commissioner Krissy Barrett said.

“The motivation is still being assessed,” Barrett said.

“We are … working closely with our Five Eyes partners and international partners to ensure our collective powers and capabilities are drawn upon to help bring those responsible to justice,” she added. Five Eyes is an intelligence-sharing partnership that includes Australia, the United States, Britain, Canada and New Zealand.

Barrett declined to say who the offshore suspects were or identify the countries they were operating in.

Two weeks ago, a 20-year-old man was charged with stealing the car used in the synagogue attack. But that suspect has not been accused of being one of the masked men who used brooms to spread a liquid accelerant across the floor of the synagogue before igniting it.

A wave of antisemitic attacks has roiled Australia since the Oct. 7, 2023, Hamas assault on Israel triggered the war in Gaza. The synagogue attack is the only incident that has been classified as an act of terrorism, a designation that increases the resources available to the investigation.

Home Affairs Minister Tony Burke welcomed the arrest in connection with what he described as a “hate crime.”

Burke noted that his government had promised 30 million Australian dollars ($20 million) to rebuild the synagogue.

“This arrest cannot undo the pain and fear that it (arson) caused, but it does send the strongest message that this kind of hate and violence has no place in Australia,” Burke told Parliament.

“This attack was not simply an attack on Jewish Australians An attack on a synagogue is an attack on Australia and is treated as such,” he added.

Daniel Aghion, president of the Executive Council of Australian Jewry, the main advocate for the nation’s Jewish community, hoped more arrests would be made and that the masterminds of the crime would be quickly brought to justice.

“Only then will a deterrent be established against this sort of chilling behavior,” Aghion said.