Niederbrock has been tentatively identified as one of four people discovered the day before in Farmville, about 50 miles west of Richmond, at the home of Longwood University professor Debra Kelley. However, Farmville police Capt. Wade Stimpson emphasized that the state medical examiner's office would not officially identify any of the victims until at least Monday.
McCroskey will be formally charged with the other three killings once the bodies are identified, Stimpson said. He said "there are a number of factors relating to why" police couldn't identify the victims. He would not say how they were killed.
Police went to Kelley's home Thursday after a West Virginia woman called to say that it had been days since she heard from her teen daughter, who was staying with Kelley and Niederbrock's daughter, Emma, Stimpson said.
Investigators went to the home, where a man matching McCroskey's description told them the girls had gone to the movies. When the mother still didn't hear from her daughter Friday, police went to the home and found the bodies.
Police arrested McCroskey at the Richmond airport Saturday as he waited to take a plane back to California. He is being held in the Piedmont Regional Jail and has an initial court appearance on Monday to determine if he needs a court-appointed attorney. Stimpson said messages posted online led police to believe McCroskey knew Emma Niederbrock and that he may have been visiting her.
On McCroskey's MySpace page, someone who goes by Ragdoll, which friends identified as Emma Niederbrock, wrote several messages to McCroskey. In a post dated Sept. 7, Niederbrock says she is excited for McCroskey's visit to her house.
"The next time you check your myspace, YOULL BE AT MY HOUSE!" the post reads.
A friend said McCroskey, Emma and her friend were brought together by horrorcore music, which sets violent lyrics to hip-hop beats.
Andres Shrim, who owns the small, independent horrorcore music label Serial Killin Records in New Mexico and performs under the name SickTanicK, said he saw all three Sept. 12 at an all-day music festival in Southgate, Mich.
Shrim said despite the morbid music he and his friends loved, they were not violent people.
"You look at the music we do and it's kind of harsh and somewhat brutal at times, but there's a different side of life that people aren't normally accustomed to, and being an artist I think it's important to see both sides of life," he said.
McCroskey recorded songs that spoke of death, murder and mutilation under the name Syko Sam. His MySpace Web page said he has only been rapping for a few months but has been a fan for years of the horrorcore genre.
"You're not the first, just to let you know. I've killed many people and I kill them real slow. It's the best feeling, watching their last breath. Stabbing and stabbing till there's nothing left," McCroskey sings in "My Dark Side."
Shrim asked others not to judge McCroskey by the lyrics to his songs or his disturbing Web pages.
"This is not something from the Sam I know," he said. "This is not something that I would ever, ever in a million years envision him doing."
Stimpson called McCroskey's songs and writings "a little disturbing," and said police were looking into that.
A phone message left Sunday at McCroskey's California home was not immediately returned.