A worldwide Jewish rights organization is pushing Hungarian authorities to prosecute a man it claims is a Nazi war criminal, recently discovered in Budapest, Hungary, who allegedly sent more than 15,000 Jews to Auschwitz in the spring of 1944.

The Simon Wiesenthal Center found Ladislaus Csizsik-Csatary as part of its "Last Chance" project, said Efraim Zuroff, director of the center's Israel office.

The center cooperated with British tabloid The Sun to photograph Csizsik-Csatary, who reportedly is 97, and ask him questions, Zuroff said. "We're the ones who found him; they're the ones who photographed him."

Csizsik-Csatary served as a senior Hungarian police officer in the city of Kosice, which is now in Slovakia but was under Hungarian rule in the 1940s, the center said. He topped the Wiesenthal Center's 2012 list of most wanted Nazi war criminals.

"He was a commander of a ghetto," Zuroff told CNN.

Csizsik-Csatary participated in the deportation of 15,700 Jews to the Auschwitz concentration camp in 1944, witnesses have told the center. He also played a role in "deportations to the Ukraine to be killed -- 300 Jews," Zuroff said.

"We found eyewitnesses on three different continents," Zuroff said. Those witnesses told the center about Csizsik-Csatary's cruelty to Jewish detainees and his role in the deportations to Auschwitz and Ukraine.

Confronted by a Sun reporter, Csizsik-Csatary denied the allegations, the tabloid reported Sunday.

A witness to the August 1941 Ukraine deportations had nine family members who were deported, he told CNN. Csizsik-Csatary made sure four of them were brought back from forced labor with the Hungarian army so they would be deported and killed, according to Zuroff.

During the Auschwitz deportations, Csizsik-Csatary "forced these girls to dig a ditch with their hands -- young Jewish girls." Two of the center's witnesses were survivors of that deportation, he said.