The mother of Washington intern Chandra Levy says she'd like to believe Ingmar Guandique is responsible for her daughter's death, but admits she has a sliver of doubt.

Asked if she felt 100 percent certain the right man had been convicted of the crime, Susan Levy said on CBS' "The Early Show" Monday that, "To be honest, I always have that 5 percent of not being sure."

Guandique was sentenced Friday to 60 years in prison. He was convicted in November of first-degree murder in Levy's 2001 disappearance and death, despite a lack of witnesses and no DNA evidence linking him to the crime.

During Friday's sentencing hearing, Susan Levy told Guandique he was "lower than a cockroach" and called him a "hideous creature."