The disappearance of World War II hero Raoul Wallenberg took an even deeper toll on his family than previously thought, his half-sister Nina Lagergren said Monday, confirming a newspaper report that her parents committed suicide.

Citing previously unseen family documents, The Wall Street Journal reported that Wallenberg's mother Maj von Dardel and his stepfather Fredrik von Dardel killed themselves by overdosing on prescription drugs in 1979.

'That's correct," Lagergren, who turns 88 on Tuesday, told The Associated Press.

Wallenberg, who worked as a Swedish diplomat in Budapest, is credited for having saved the lives of at least 20,000 Jews during WWII and averted the massacre of 70,000 more people in Budapest's ghetto. He was recruited and financed by the U.S. and was arrested by Soviet troops in 1945.

The Russians say Wallenberg died in prison in 1947, but never produced a proper death certificate or his remains.

"When he did not return home, it became a tragedy for the entire family, but most of all for him himself," Lagergren said.

The Wall Street Journal, which studied a 50,000-page archive compiled by Wallenberg's half-brother, Guy von Dardel, said Maj and Fredrik von Dardel committed suicide two days apart, devastated by decades of conflicting reports about Wallenberg's fate. They were 87 and 93.

Asked why the family had not revealed the cause of death before, Lagergren said there was no reason to talk about it.

She accused Moscow of giving misleading information about Wallenberg's fate.

"It has been a fight against a giant, and as far as we understand it they have been lying all the time," Lagergren said, also blaming Swedish officials for not doing enough to investigate her brother's fate.

"It is easy for his story to be forgotten, but we think it is important. He is a good role model," she said.