EL CAJON -- A registered sex offender allegedly linked to the presumed slaying of a 24-year-old Santee woman pleaded not guilty Friday to a murder charge.

Robert Steven Carson, 40, was arrested at his Spring Valley home on Tuesday after investigators executing a search warrant found a large quantity of blood in the basement, prosecutor John Rice told Superior Court Judge Patricia Cookson.

Carson allegedly tried to call someone to come clean up the blood on May 25, a day after Brittany Hart went missing, Rice said.

Hart and her 1998 Ford Ranger pickup have not been found, and authorities don't believe she's still alive.

Rice told the judge that Carson had five felony "strikes," including a 1986 conviction for assault with intent to commit rape against three separate victims.