Virginia Tech gunman Cho Seung-hui was diagnosed with autism after the family emigrated to the United States, a relative in South Korea said.

"From the beginning, he wouldn't answer me," Kim Yang-soon, Cho's great aunt, said in an interview Thursday with Associated Press Television News. He "didn't talk. Normally sons and mothers talk. There was none of that for them. He was very cold."

"When they went to the United States, they told them it was autism," said Kim, 85, adding that the family had constant worries about Cho.

Cho's uncle gave a similar account, but said there were no early indications that the South Korean student who killed 32 people and himself at Virginia Tech University in the U.S. had serious problems. The uncle asked to be identified only by his last name, Kim.

Cho "didn't talk much when he was young. He was very quiet, but he didn't display any peculiarities to suggest he may have problems," Kim told The Associated Press in a telephone interview Thursday. "We were concerned about him being too quiet and encouraged him to talk more."

Autism is a neurodevelopmental disorder that encompasses a broad range of symptoms frequently including impaired social interaction and communication, as well as obsessive interests and behavior. Autism remains a topic of heated debate in the scientific community, where little is understood about its cause.

Cho left South Korea with his family in 1992 to seek a better life in the United States. Since the shooting, the U.S. government has been providing protection for Cho's parents, South Korea's ambassador to Washington said Friday.

"We've confirmed that the parents are being safely protected by U.S. investigative authorities," Ambassador Lee Tae-sik told MBC Radio.

Lee said U.S. authorities declined to say where the parents were "because they move from place to place everyday."

Kim, the uncle, said the family never visited their homeland that he did not recognize his nephew when his picture appeared on television as the culprit in the deadliest shooting rampage in U.S. history.

"I am devastated," Kim said between heavy sighs. "I don't know what I can tell the victims' families and the U.S. citizens. I sincerely apologize ... as a family member."

In South Korea, Cho's parents ran a small book store in Seoul, Kim said. The family lived in a two-room apartment no larger than 430 square feet.

"They had trouble making ends meet in Korea. The book store they had didn't turn much profit," Kim said.

He said his sister — Cho's mother — occasionally called around holidays, but never mentioned having any problems with her son.

"She said the children were studying well. She didn't seem worried about her children at all," Kim said. "She just talked about how hard she had to work to make a living, to support the children."

He said he has been unable to reach Cho's mother since Monday's massacre. She and her husband now work at a dry cleaners in suburban Washington.

Meanwhile, the headquarters of South Korea's largest Buddhist sect, Jogye, held a memorial service for the Virginia Tech victims, offering flowers and incense on a mourning altar. Hanging in the temple's courtyard were 33 white lotus lanterns with the names of the dead, including the killer, Cho.

"They're all like my children. I will pray for the poor souls who lost their lives to reach nirvana," Buddhist follower Lee Yeon-sook, 68, said during the service.