ABCNews has obtained new court documents that show police are probing the possibility that Seung-Hui Cho may have confided to someone else his plans to unleash a bloody campus massacre that left 32 victims dead earlier this week.
In a search warrant affidavit filed by Virginia State Police Friday, authorities say the shooter "may have communicated with others concerning his plans to carry out attacks on students and faculty at Virginia Tech."
Police are now seeking Cho's cell phone records from Verizon Wireless in New Jersey.
The court documents also provide insight into Cho's relationship with his parents, who, along his older sister, released the family's first public statement Friday afternoon. "He normally spoke to his parents on Sunday evenings," the affidavit reads.
In another warrant affidavit filed Friday, police seek to mine Virginia Tech's computer servers, to see if Cho may have communicated by e-mail with Emily Hilscher, one of two victims shot in Ambler Johnston Hall.
The affidavit says that "there is probable cause to believe the computer information maintained by Virginia Tech for Seung-Hui Cho and victim Emily Hilscher, may contain information relating" to the shootings. The warrant also cites a criminal investigative analyst who tells police "that in 80 to 85 percent of homicide cases the victim is known to the offender."
On Thursday, Virginia Tech police seized Hilscher's laptop computer and her cell phone.
ABC News has also learned police have obtained a medical and a counseling file for Cho from Schiffert Health Center at Virginia Tech, suggesting the 23-year-old killer may have worked with campus counselors — something that has not yet been confirmed by university officials.