Officials in Bulgaria said the man arrested in connection to Friday's shootings visited the country last year.
As details emerge over the suspect charged for the massacre at two mosques in New Zealand, countries in Europe have launched a probe into 28-year-old Brenton Harrison Tarrant's ties to the region.
The Australian national wrote in a 74-page manifesto circulated online that he was born into "a working class, low income family" and skipped university to work and deal in cryptocurrency.
Tarrant also wrote that he used the money he made from his dealings to fund his travels to France, Spain, and Portugal in 2017.
Several other countries also checked their records to see if he had embarked on other journeys.
Tarrant's 'very serious knowledge' of Balkan history
It was revealed that in 2016, he visited Serbia, Montenegro, Bosnia and Herzegovina, and Croatia, where he stopped by historic battle sites, according to Bulgarian Prosecutor General Sotir Tsatsarov.
Tsatsarov said investigators are now working to determine if Tarrant had any ties with Bulgarians and are working with partners across the world, including Serbia and the US.
The Prosecutor also said Tarrant returned to the region in November 2018 to visit historic sites of Bulgaria, Romania, and Hungary.
His interest showed “a very serious knowledge of the Balkan history in details I would say even few people in the Balkans know,” Bulgarian Foreign Minister Elaterid Zachariah told Reuters.
Bulgaria's Interior Minister Mladen Marinov said in a statement released to news agency BTA: "We express our deepest condolences and do not want Bulgaria, which is an ethnically tolerant country, to be associated in any way with this horrible and unjustifiable act."
Tarrant also visited Turkey multiple times, including an "extended visit", a senior Turkish official confirmed to the Associated Press on Saturday but would not confirm the dates of the travels.
The official also said an investigation into "the suspect's movements and contacts within the country" were underway.
Trip to Pakistan
According to New Zealand's Herald newspaper, Tarrant's suspended Facebook page also showed a post from Pakistan in 2018, where he said the country “an incredible place filled with the most earnest, kind hearted and hospitable people in the world”.