New Delhi: Denial of opportunity to cross- examine a key prosecution witness on material aspects had "vitiated" the trial in the 2002 Nitish Katara murder case, convict Vikas Yadav told the Delhi High Court on Sunday.

"If I am not permitted to cross-examine a material witness on material aspects then the trial becomes vitiated," advocate U R Lalit, appearing for Vikas, told a bench of justices Gita Mittal and J R Midha.

Continuing final arguments for the fifth day, Lalit said the trial court had relied upon the testimony of key witness Ajay Katara who had allegedly seen Nitish alive last in the company of Vikas, Vishal Yadav and Sukhdev Pehalwan in a Tata Safari on the night of February 16-17, 2002 near Hapur octroi post.

The statement was relied upon by the trial judge as the "last seen evidence" to link the offence with the accused.

The questions about his vision and visibility and the evidence of the witness with regard to the accused and the victim were "crucial," he said, adding that the trial judge ordered that no such queries would be allowed.

"All our questions on this issue were stalled at the threshold when it is on record that the gentleman ( Ajay Katara) recorded his statement during the trial with his goggles on," Lalit said.

The prosecutor, during the trial, had asked leading questions from witnesses including Ajay Katara, he said, adding that such evidence cannot be considered.

Earlier, Vikas, son of UP politician D P Yadav, his cousin Vishal and Sukhdev Pehalwan were awarded life term for killing Katara, a business executive, after abducting him from a marriage party at Ghaziabad on the intervening night of February 16-17, 2002.

The final arguments in the case remained inconclusive and would continue on Tuesday.

Earlier, Vikas had alleged that the lower court had disallowed crucial questions put to key witness Ajay.

The trial court, in its judgement on May 28, 2008, had relied on various circumstantial evidence including the testimony of Ajay.

The statement was relied upon by the trial judge as the "last seen evidence" to link the offence with the accused.

The counsel for Vikas had also referred to the testimony of Bharti Yadav and had said the prosecution had failed to establish the motive which prompted the convict to kill the Nitish Katara.

The prosecution had said Katara was killed for his alleged intimacy with Bharti.

The convicts had moved the high court seeking reversal of the trial court's findings. Police and Neelam Katara have filed appeals for award of death penalty, saying the offence was of the "rarest of rare" category.