Dylan Quick also told an investigator that he had researched mass stabbings on his home computer about a week before the attack at Lone Star College in Cypress, according to a search warrant affidavit.
"He stated that he had read numerous books about mass killings and serial killers which are also located at his residence," the affidavit said.
Quick is being held without bond on three counts of aggravated assault with a deadly weapon for Tuesday's attack that injured 14 people. Only one person remained hospitalized Thursday, and that person was listed in good condition.
Quick's attorney, Jules Laird, said after a court hearing earlier Thursday that he was still looking into his client's background. Laird said he didn't think the 20-year-old had a history of mental illness. But he said Quick was on suicide watch and will stay in jail as he undergoes a psychological evaluation.
"Not every question has an answer that satisfies you or that says this is the root cause of why he did this ... with a knife. We are going to see if we can reach that," Laird said.
The affidavit released later in the day named nine items that were seized from Quick's home, including one listed as "Hanibal Lecter Mask." Hannibal Lecter is the cannibalistic serial killer from the 1991 movie "The Silence of the Lambs."
Other items seized included a laptop, an animal dissection kit and several books, including ones called "Hit List" and "Hitman." The affidavit does not say what the books are about.
Laird had described Quick as a voracious reader who had thousands of books.
The affidavit said Quick told the investigator that in preparing for the campus attack, he had sharpened various things, including a hairbrush and pencils, to use as weapons. However, authorities have said Quick used only a razor utility knife to slash at his victims on two floors of the college's health science building. They said a scalpel was found in a backpack he was carrying when he was arrested.
Authorities have said students tackled Quick and held him down outside the building until police arrived. Texas does not permit people to carry handguns on campuses, but lawmakers are considering allowing concealed permit holders to take their weapons into college buildings and classrooms.
A Texas House panel approved such a bill Thursday, sending it to the full House. Supporters say it's a self-defense measure that will help prevent campus shootings and assaults. Opponents argue that allowing guns into campus buildings increases the chances for violence.
Quick had been set to make his first court appearance Thursday, but Laird waived the reading of the probable cause statement so his client would not have to be in court. Quick's next hearing is May 10. If convicted, Quick faces up to 20 years in prison.
"We just didn't want to have a media circus at this point in time," Laird said.
When asked about claims by the Harris County Sheriff's Office that Quick admitted to having fantasies about stabbing people since he was 8 years old, Laird said, "They've got a statement from him, but that's not the whole story."
"There are other things that I need to find out about and then we will provide the whole story to the public so that they can understand what happened," he said.
Laird said Quick had been home-schooled for most of his life and that he had been enrolled at Lone Star in part so he could be around other people and "get some type of feel for what the rest of the world is like as opposed to just living at home ... and being home-schooled by his mother."
Laird said Quick's parents hadn't had any major problems with their son, though he did apparently go missing for a few days in January 2011.
Quick's parents had contacted Texas EquuSearch, a private Houston-area group that searches for missing people, after getting a text message from their son saying "he was leaving because he might possibly harm himself," said Frank Black, a case adviser with the organization.
Black said he and others with his group were set to begin a search for Quick when his parents contacted them three days after the initial report, saying they had found their son and he was safe.
Quick had apparently been staying on the Lone Star college campus and some security guards had given him food and a tent to sleep in, Black said.
Laird said Quick's parents are devastated by the accusations made against their son.
Quick's mother is "the person that knows him more than anybody else in the world. And so, what she knows of him does not fit with what happened (Tuesday). She loves him dearly and his dad loves him dearly. And both of them do not understand what happened," he said.
Associated Press writer Jim Vertuno in Austin, Texas contributed to this report.