The inauguration of a new Chilean president on Saturday could help solve the 21-year mystery of a missing Penn State professor who disappeared while hiking in Chile in 1985.

Boris Weisfeiler, 43, a Russian-born mathematics professor, was vacationing in Chile in January 1985 when he disappeared. A search was launched when he failed to show up for spring classes. The Chilean government initially concluded that he drowned while crossing the Los Sauces River.

Olga Weisfeiler, Boris' sister, said she has been working for the past two decades to continue an investigation into the disappearance, which she is certain is connected with Colonia Dignidad -- an area where it is believed that the Chilean government, under dictator Augusto Pinochet, held and tortured political prisoners.

Pinochet came to power in Chile after a violent coup in 1973 and was known to commit extensive human rights violations during his presidency until 1990.

During Pinochet's years as president, 1,100 people disappeared. Boris Weisfeiler is the only known American citizen among those missing.

According to declassified U.S. documents, Chilean insurgents may have mistaken Weisfeiler for a U.S. government agent or a Russian spy.

Olga Weisfeiler said she has spoken with the first Chilean female president, Michelle Bachelet, about focusing on the investigation. The two first met while Bachalet was the minister of defense.

Olga Weisfeiler will travel to Chile in the coming weeks to speak personally with the new head of state, she said.

"I am going to try to push the investigation forward with the meeting," she said.

Bachelet was imprisoned and tortured during Pinochet's rule before being forced into exile in Europe and Australia in 1975, The Associated Press reported.

Penn State spokesman Bill Mahon said the university is not actively involved in the case at this time but has made inquiries over the years to see resolution in the case.

"We certainly would welcome any movement to discover what happened with Dr. Weisfeiler," Mahon said. "It has been a very strange case ... and odd stories have surfaced over the years about what may or may not have happened. It would be great for the family and friends to have some closure."

In response to Bachelet's election, several U.S. congressmen have contacted Secretary of State Condoleezza Rice in support of prioritizing the investigation.

U.S. Sens. Arlen Specter, R-Pa., and Rick Santorum, R-Pa., and U.S. Rep. John Peterson, R-Pa., are among 14 people to sign a letter addressed to Rice "to urge a renewed focus."

The letter, sent to Rice on March 8, recognizes that the case was reopened in January 2000, but with few new developments besides investigations of several judges involved in the case.

The group asked Rice to make the disappearance one of her priorities during discussions with Bachelet, which occurred on Sunday.

"We're not looking for something that cannot be delivered," Peterson said in a press release. "We just want answers, and I think Boris' family, friends and former students are, in the very least, entitled to those."

Rice has not revealed publicly what she and Bachelet spoke about in their meeting.

Olga Weisfeiler said she believes the new president will be willing to help as much as possible to bring closure to the case. "It was a case of [Boris] being in the wrong time, wrong place," she said.

The Associated Press contributed to this report.