A criminal expert has gone on trial in Ukraine accused of raping and murdering dozens of young women and girls over a period of 25 years, prosecutors said Friday, AP reports.

Sergei Tkach has been charged with multiple premeditated murders and prosecutors have evidence he committed at least 60 rapes, murders or both, said Yuriy Boychenko, a spokesman for the Prosecutor General`s Office.

Authorities say Tkach, who has training in criminal investigation, has confessed to more than 100 rapes or murders, and investigators are working to verify his claims.

A court in the eastern city of Dnipropetrovsk began hearings Wednesday, Boychenko said. The trial, conducted behind closed doors as it involves minors, is expected to last several months. Tkach faces life in prison if convicted.

Prosecutors say Tkach, a gray-haired man in his fifties who is originally from Russia, committed his first crime in 1980. But he was not arrested until August 2005, when a surviving victim gave authorities enough information to identify him, according to Boychenko.

He said Tkach`s experience as a criminalist helped him escape prosecution for so many years.

"His professional skills helped him conceal his crimes," Boychenko said.

Ukraine`s most notorious serial killer to date, Anatoly Onoprienko, was arrested in 1996 and eventually convicted of murdering more than 40 people over about a decade.

He was sentenced to death, which was commuted to life imprisonment after Ukraine suspended capital punishment.