Police shot and killed 32-year old Castile late on July 6 after pulling his car over for a broken tail light.
"With respect to the next steps and the legal actions, yes, we will aggressively pursue justice on [Philando Castile] his behalf. Yes, there will be a lawsuit," Hatchett told reporters. "We will not share those details of the lawsuit now."
The family attorney called for an independent prosecutor to be brought in to handle any criminal case against the police department.
Additionally, Castile’s mother, Valerie, stated that the United States must enact new laws to prevent more African-American men from being killed by police. She described Castile as a "pillar of the community" in Falcon Heights.
Hatchett stressed that Castile was complying with police orders when the African-American was killed.
The deaths of Castile and another African-American man, Alton Sterling, sparked widespread protests in the United States last week, with demonstrators marching in dozens of US cities throughout the weekend.