New Delhi: A mentally disturbed youth from UP was behind the murder of a college girl in Delhi as he wanted to avenge the humiliation he suffered when he was beaten up for stalking her three years ago, police said on Friday.

Twice in a month, young Radhika Tanwar came deadly close to her death as her "murderer" followed her waiting for a chance to kill her.

The third time, the 20-year-old degree student was not so lucky as she fell to the bullets of her alleged stalker Ram Singh alias Vijay on a foot-over-bridge outside Ramlal Anand College in south Delhi's Dhaula Kuan on Tuesday.

According to investigators, Vijay allegedly followed Radhika at least twice with an intention to kill her in the past one month, the last one being three days before her murder.

Vijay allegedly nurtured "deep grudge" against Radhika after he was beaten up for harassing her three-and-half-years ago and used to tell his friends that whenever he would get an opportunity, he would take revenge. He felt insulted and left Delhi's Naraina for Mumbai.

"We have learnt that a month ago, he had boarded a bus in which the victim was travelling. However, he could not execute his plans. Last Saturday, he followed her on the foot-over-bridge," H G S Dhaliwal, Deputy Commissioner of Police (South), told reporters.

Vijay is a "drunkard" and was never regular at his work. His previous employer Kamal even did not provide him a job when he returned to the capital due to his "character", a senior police official said.

"He is not in regular touch with his family. He was even involved in stalking of women in his village," the official said.

According to Dhaliwal, they identified the suspect following extensive investigations in Naraina area from where three incidents of beating up of stalkers took place but not reported to police.

"Those involved in these incidents did not approach police and we do not have any documentation regarding it. We spoke to polling agents of political parties who knew the voters in the area as well as those who did not figure in the voters list.

"We also spoke to owners of ration shops, grocery shops and milk booths who provided inputs about friends of those who were beaten up," Dhaliwal said.

Investigators said that they faced tough times as the owners of knitting and fabrication units operating in Naraina area do not maintain a register of their employers. Moreover, the workers also shifted jobs very fast.

"For many reasons from avoiding inspectors and ESI officials to evading tax, they do not maintain proper records. In last three years, the particular unit where Vijay was working changed three hands. The workers also changed units in 45 days," Dhaliwal said, adding at least 2,000 workers have come and gone in the area.

Residents, students stage protest

Earlier in the day, the residents of Radhika’s area had staged a road blockade demanding immediate arrest of her killer. Residents staged a protest and blocked the Outer Ring Road in Naraina in west Delhi. Students had also held protests in various colleges demanding the arrest of the culprit.

BJP's student wing ABVP had called for a strike in Delhi University to protest the incident and demand more security for students.

Concern in LS

Concern was raised in the Lok Sabha also over the killing of Radhika with members demanding a statement from the government on crime against women in the capital as well as the entire country.

The issue was raised by unattached member Jaya Prada, who slammed the UPA government for not being able to stop atrocities against women.

She said, "In Delhi a girl student was shot in broad daylight. 38 hours have gone by, yet no headway has been made in the case."

Jaya Prada, who was expelled from the Samajwadi Party, also said that the situation was equally bad in states of Uttar Pradesh, Orissa and Andhra Pradesh.

Members cutting across party lines supported her demand with SP MP Shailendra Kuamr demanding a statement on the issue from the government.

Minister of State for Parliamentary Affairs V Narayanasamy said he would convey the concern of the members to the Home Minister.