Knox's Mom: No Hint Of Her At Murder Scene

Amanda Knox's mother is trying to punch holes in the prosecution's murder case against her daughter.

Knox, from Seattle, is on trial along with Italian ex-boyfriend Raffaele Sollecito for allegedly killing Meredith Kercher, Knox's British roommate in the central Italian town of Perugia.

Knox's mother, Edda Mellas, testified Friday and was in court as a spectator on Saturday.

Speaking from outside the courthouse, Mellas told Early Show Saturday Edition co-anchor Chris Wragge, "One of the big things you don't hear a lot about is the fact that, at the actual crime scene, there's no, no physical evidence of Amanda - not a hair, not a fingerprint ... nothing.

"The DNA (prosecutors say was found at the scene) is so insignificant - it's this tiny spot, it's not blood, it could well have come from ... who knows where."

The trial is now examining forensic evidence, CBS News correspondent Allen Pizzey reported from Perugia Saturday, and the Kercher family has asked that it not been made public. Some of it, Pizzey says, is so graphic it made one jury member ill.

A coroner told a jury Saturday that a stab wound to Kercher's neck was caused by a shorter knife than the one believed to be the murder weapon, news reports said.

Prosecutor say Kercher's DNA - and Knox's - was found on the longer knife.

Francesco Introna, on the witness stand Saturday, also said no more than a single attacker could have assaulted the victim on the night of the 2007 slaying, the ANSA news agency said.

Kercher's body was found in the apartment she shared with Knox on Nov. 2, 2007.

Knox and Sollecito both deny wrongdoing. They are charged with murder and sexual violence in what prosecutors assert began as a sex game.

Introna, who was called to the stand by Sollecito's defense lawyers, testified that the cut on Kercher's neck was made with a knife with a 3 - 3-1/2-inch-long blade, ANSA said.

Prosecutors say that a 6-1/2-inch knife found at Sollecito's house matched the victim's wounds and could be the murder weapon. They say the knife had Kercher's DNA on the blade and Knox's on the handle.

A third person, Rudy Hermann Guede of the Ivory Coast, was convicted in a separate trial last year and sentenced to 30 years in prison. He denies wrongdoing and has appealed his conviction.

Introna said that the bedroom where Kercher was killed was too small and that it would be "physically impossible" that three people could have attacked her, ANSA said.