The mother of a U.S. Navy veteran who has been detained in Iran since last summer is begging authorities there to free her son. Iran's foreign ministry spokesman confirmed Wednesday that Iran arrested Michael White "some time ago" and said the 46-year-old is being investigated, though he didn't say for what.

Michael's mother, Joanne White, told CBS News her son had traveled to Iran three times to visit an Iranian woman he met online. After Michael didn't board his flight back from a trip last July, his mother filed a missing persons report. But she said she only heard from the U.S.State Department about three weeks ago.

At about the same time, a former inmate who said he met Michael in prison broke the news of Michael's detention on Twitter. CBS News' Roxana Saberi spoke with that former inmate, Ivar Farhadi, who told her Michael was suffering psychologically and was being held with dangerous criminals. Asked if Michael had been physically tortured, Farhadi said he couldn't discuss that subject with Michael because they were being watched.

The State Department has not commented on any ongoing efforts to secure his release.

Michael's detainment echoes the case of Roxana Saberi herself, who was imprisoned by Iranian authorities for 100 days in 2009 on a false charge of spying for the CIA. Saberi described what Michael could be facing during his detainment and the psychological challenges she encountered in custody.

"There is a pattern. Typically, you're first put in solitary confinement where you're cut off from the outside world. You don't get any phone calls. You don't have access to an attorney, which is the experience that White had, according to the former inmate who met him in prison. You also undergo intense interrogations. In my case, I was blindfolded facing a wall and pressured to make a false confession. Prisoners also report being tortured, whether it's physical or psychological. The hardest part for me was to be in solitary confinement because you have no one to talk to except yourself, and you have nothing to do except think and usually what you think about is how worried your family is about you, especially when they don't know where you are. They could even think you're dead, which all makes you a lot more vulnerable to the pressures of prison."

To this day, Saberi said she is still uncertain why Iran believed she was a spy to begin with.

"I do know that it is a fairly common accusation that the Iranian authorities make against dual nationals, Iranian-Americans as well as Americans, and they often fabricate evidence and put you under pressure, as I said, to make false confessions. Without an attorney, it's very hard to defend yourself."

Ivar Farhadi said he met Michael White in Vakilabad Prison in Mashhad. Jasmin Ramsey of the Center for Human Rights in Iran said that prison is overpopulated, resulting in prisoners being forced to sleep on the ground, poor nutrition, and medical services that don't meet standards set by the U.N.

Ramsey also noted Iranian law requires violent and non-violent convicts to be held in different wards for safety reasons. Farhadi said Michael was being detained with dangerous criminals.