Two Syrian nationals linked to terror groups were arrested Thursday in Germany and a third Syrian was arrested on suspicion of murder as Chancellor Angela Merkel's government continues to juggle its international role as a beacon of hope for immigrants with intense domestic demands to combat terrorism.

In the eastern German city of Cottbus, Mayor Holger Kelch called for calm after a Syrian teen was arrested in connection with the murder of Gerda Kruger, 82.

The suspect arrived in Germany in 2015, but he is a juvenile and so few other details were released by prosecutors in Cottbus, a city of 100,000 people about 75 miles southeast of Berlin, the Berliner Morgenpost reported. No motive was released.

Prosecutor Gernot Bantleon said the maximum penalty for a juvenile would be 10 years.

"We know that the origin of the alleged perpetrator will arouse emotions," Kelch said on the town's website after the arrest late Wednesday, adding the "single young man has used hospitality, openness and tolerance in Cottbus in the most brutal and disgraceful way."

Kruger lived in the city and knew the suspect, police said. A relative found Kruger's body at her home in December after she failed to appear at a Christmas celebration with former work colleagues. The cause of death was not released.

Kelch stressed that all foreigners living in Cottbus should not be "under general condemnation" because of the crime.

On Thursday, German authorities arrested a Syrian national on war crimes charges linked to the killings of dozens of civilians in Syria in 2013 as a member of the al-Nusra Front terrorist group, prosecutors said. Germany's DPA news agency said a man identified only as Abdalfatah H A, in accordance with German privacy laws, was arrested in Dusseldorf. He was linked to the execution of 36 Syrian government employees in 2013.

According to German news magazine Der Spiegel, Abdalfatah H A, 35, came to Germany as an asylum seeker.

Another suspected al-Nusra Front fighter — Abdulrahman A A, 26, charged with membership in a foreign terrorist organization — was arrested in the town of Giessen, about 120 miles southeast of Dusseldorf. Al-Nusra was al-Qaeda's affiliate in Syria but has at times fought alongside western-backed rebel groups attempting to oust Syrian President Bashar Assad.

Germany has accepted more than a million immigrants, mainly from Syria, Iraq and Afghanistan, in the past two years. Merkel has been under political siege following a series of terror attacks, including a December incident in which a truck slammed into a Christmas market in Berlin, killing a dozen people and injuring scores more.

The suspect in the market attack was a Tunisian whose asylum application was turned down because authorities suspected he may have become radicalized. Efforts to deport him were delayed because of a paperwork mix-up. He was found four days after the attack in Italy, where he was killed in a shootout with police.

Last month, police in the German city of Braunschweig canceled a Carnival street parade after police said they received a "concrete threat of an attack."