Walker's family is suing the Pennsylvania Board of Probation and Parole.
The suit says Walker's accused killer, 23-year-old Rafael Jones, should not have been on the streets.
It says Walker's death on August 18th could have been prevented had Jones been locked up days earlier for a probation violation.
"Officer Walker's murder occured as a result of a systemic breakdown at the defendant board," said Walker family attorney Michael F. Barrett.
The family also says proper policies and procedures weren't in place to keep Walker and the community safe from Jones.
The board of probation and parole is declining comment until officials get to read the full lawsuit.