Hungary said Monday it is investigating whether a Holocaust-era war criminal has been living in the capital, Budapest, as international and domestic groups clamored for him to be placed on trial. Budapest prosecutors said in a statement that they were investigating a case based on information received from Efraim Zuroff, head of the Simon Wiesenthal Center\'s Jerusalem office, but did not name the suspect. The center has told prosecutors that a man named Laszlo Csatary living in Budapest is believed to be the same Laszlo Csatary who was police chief in 1941 in the Slovakian city of Kosice, then part of Hungary, where he played a \"key role\" in the deportation of 300 Jews to Ukraine, where they were killed. Csatary, who the center says would now be 97 years old, is also suspected of helping to organize the 1944 deportation of some 15,700 Jews to Auschwitz. A group of students held a protest Monday at an apartment building in Budapest where Csatary is thought to have lived until recently, while the opposition Socialist Party called on Chief Prosecutor Peter Polt to indict him for war crimes. Csatary was nowhere to be seen, and officials have not provided any information as to his whereabouts. In April, a man named Ladislaus Csizsik-Csatary was placed at the top of the Wiesenthal Center\'s list of its most wanted war crimes suspects. Csizsik-Csatary had been convicted in absentia for war crimes in Hungary in 1948 and sentenced to death. He arrived in Nova Scotia the following year, became a Canadian citizen in 1955 and worked as an art dealer in Montreal. In October 1997, Canadian authorities said the 82-year-old had left the country, apparently bound for Europe, before they had the chance to decide his fate in a deportation hearing. His citizenship had been revoked in August and the deportation order was based on his obtaining citizenship through \"false representation or fraud or knowingly concealing material circumstances.\" Zuroff, the center\'s self-described chief Nazi hunter, said a paid informant had provided the information last September that Csatary was living in Hungary and apparently had done so since leaving Canada in the 1990s. \"His information has been super-reliable,\" although he will not receive any money unless Csizsik-Csatary is convicted and punished, Zuroff said Monday in a telephone interview with The Associated Press. He declined to name the informant, or say how much he would receive. Some 40 protesters gathered at the Budapest apartment building Monday, among them members of the European Union of Jewish Students. They formed a line by binding their wrists to each other with tape and shouted \"Never again!\" One of the protesters put a crossed out swastika sticker on the door of the second floor apartment where Csatary is thought to have lived. \"We came here because we want the Hungarian organs of justice to start a process against this war criminal,\" said Krisztian Szilberhar, a young lawyer who participated in the protest. \"He is responsible for the death of many innocent people.\" Considering Csatary\'s age, \"it would be enough justice if they declared him guilty and he had to continue to live here,\" Szilberhar said. Deborah Abisror of the European Union of Jewish Students said she was disappointed that they were not able to find Csatary. \"He\'s not here, obviously,\" she said. \"He shouldn\'t move anymore. He just should confront what he did. Maybe just to say sorry.\" Zuroff said that thousands of Nazi collaborators from Eastern Europe made their way to English-speaking countries after World War II, lying about their wartime past to gain refugee status. Rabbi Slomo Koves, of the Unified Hungarian Jewish Congregation, said that members were \"pretty shocked that somebody like this is living in Budapest ... and living between us.\" \"But I think it is also in a way some relief that there are still organizations that do these jobs and that find these people,\" he said.