Investigators confirmed that Theodore Norvell, an engineering professor at Memorial University, and his sister Cindy Norvell suffered multiple stab wounds to the neck and chest in the attack at her home in Laytonville, Calif., on Sunday.
Lieut. Shannon Barney, an investigator, said the hospital has informed police that both Norvell and his sister were in stable condition on Wednesday.
A police news release says the attack resulted in the deaths of 52-year-old Coleman Palmieri, Cindy Norvell's husband, and their 17-year-old son Teo Palmieri.
Barney says Norvell's 15-year-old daughter and her 14-year-old cousin were confined during the incident.
A news release from the Mendocino County Sheriff's Office says Talen Barton, 19, of Laytonville is facing two charges of homicide, two charges of attempted murder and two charges of confinement.
Police say Barton was in the foster care system and had lived with the family for over a year and they were attempting to help him gain enrolment to a local college.
Dennis Peters, the dean of electrical and computer engineering at Memorial University, confirmed that Norvell is a professor at the university and said he was on a family visit with his sister and his daughter.