Vakhtang Makhniashvili suffers from a delusional disorder, according to the results of a psychiatric assessment that were presented in a Toronto court Thursday.
The 51-year-old was first thrust into the public eye in September 2009 when his 17-year-old daughter Mariam disappeared without a trace from outside her Toronto-area high school.
Makhniashvili was back in court Thursday for a sentencing hearing, after pleading guilty to three counts of aggravated assault this summer.
"I would like to apologize to my victims. I didn't realize how much pain and trouble I've caused to society and my family," he told the court.
Makhniashvili's charges stem from the stabbing of a former neighbour in May 2010 and the November stabbings of David and Delores Langer, a couple previously unknown to the Makhniashvilis who had stepped forward to post bail for the previous attack.
Earlier Thursday, all three victims read impact statements in court, detailing the extensive physical and emotional injuries they suffered.
Makhniashvili has told court he stabbed his 26-year-old neighbour after accusing him of being responsible for his daughter's disappearance.
He has also admitted to stabbing the Langers outside their home after blaming them for an unfavourable newspaper article about his family.
Justice Rebecca Rutherford is expected to render a decision in the case on Dec. 8.
Despite an exhaustive search, Toronto police have never been able to locate Mariam or find an explanation for her disappearance.
With files from CTV Toronto's Zuraidah Alman
