Taliesin Myrddin Namkai Meche was fatally stabbed on a Portland train while defending a Muslim girl and her friend on May 26, 2017.
The lawsuit filed by his sister, Vajra Alaya-Maitreya, claims police failed to take the suspect into custody after numerous threats to other passengers just days before the fatal attack.
The lawsuit also claims the company that operates the MAX, TriMet, failed in enforcing its own rules in protecting passengers.
A 15-month dispute between the families of Ricky Best, who also died in the MAX attack, and Namkai Meche’s was settled last summer.
According to the Oregonian, over $1.6 million was raised for the victims’ families following the incident. Nearly $600,000 donated through a GoFundMe account remained in dispute until families reached the agreement over how those funds would be divided.
The details of the arrangement have not been disclosed.