Blacksburg: The gunman who went on a rampage at Virginia Tech had been confronted by university police in 2005 over complaints of stalking two female students and was sent to a mental health facility because of worries he was suicidal, police said yesterday.

The new details added to a chilling portrait of Cho Seung-Hui, a 23-year-old South Korean student who massacred 32 people and then took his own life at the university on Monday in the deadliest shooting spree in modern US history.

Fellow students and teachers have described a troubled loner whose writings for his English degree were so laced with violence and disillusionment that they alarmed some of those around him.

University Police Chief Wendell Flinchum said his officers approached Cho in late 2005 when two women students complained of "annoying" phone calls and instant messages from him.

"I'm not saying they were threats; I'm saying they were annoying. That's the way the victims characterised them, as annoying messages," Flinchum told a news conference. After the second incident Cho's roommate told police he "might be suicidal," prompting them to issue a "temporary detention order" and send him to a mental health facility for evaluation, Flinchum said.

Authorities would not say how long Cho was evaluated. "We did not have any contact with him after December 2005 that I'm aware of at this time," Flinchum said.

Doors chained

Cho, who immigrated to the United States 15 years ago with his family and was raised in suburban Washington, DC, chained doors to prevent escape and worked his way through classrooms, shooting his victims one by one. He later killed himself.

Neighbours, roommates and teachers described Cho as a withdrawn person who rarely spoke. Two students who said they were Cho's roommates said he had harassed several female students and once told them he wanted to kill himself, which prompted the roommates to report their concerns to the police.