EL CAJON, Calif. -- 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 and clean up the blood on May 25, a day after Brittany Monet 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.

Carson had a pending case in the South Bay for evading officers when he was taken into custody in connection with Hart's disappearance.

Cookson ordered Carson held without bail. He faces life in prison if convicted.

Hart's sister, Brandy Reynolds, told reporters outside the courtroom that she was "appalled" that Carson had been free considering his criminal past.

"People like him should not be able to walk free," Reynolds said. "I don't think I've ever hated anybody in my life. I hate him."

Reynolds urged anyone who wanted to join a search party for her sister to meet at Sweetwater Regional Park at 6 a.m. Saturday.

She said her family still holds out hope that Hart is alive.

"The biggest focus right now is finding her truck ... finding her," Reynolds said.

Outside court, Rice also urged anyone who might have seen Hart or her truck to contact authorities.

Rice said there was cell phone contact between the defendant and the victim the day before she went missing, the prosecutor said.

The prosecutor said Carson -- who was sentenced to six years on the assault case in 1987 -- would have been facing life in prison if convicted of those same charges Friday.

Carson was also convicted in 2003 of misdemeanor sexual battery, Rice said.

"It's sad that anyone with that kind of record is out there committing a crime in 2007," Rice told reporters.

Cookson scheduled a June 15 readiness conference for Carson, along with a June 21 preliminary hearing.

Anyone with information about Hart or her pickup -- dark gray with red-painted door jams and license plate number 6M91555 -- is urged to call the sheriff's homicide unit at 858-974-2321 or, after hours, at 858-565-5200, or Crime Stoppers at 888-580-TIPS.