Video (02:41) : Sophia Wilansky of New York was airlifted to HCMC after being severely injured in the Dakota Access pipeline protest on Sunday.

A Dakota Access pipeline protester who nearly lost her arm after allegedly being hit by a projectile fired by law enforcement is suing the government for the return of property seized by FBI agents who visited her hospital room a day after surgery.

According to a federal lawsuit filed Friday by Sophia Wilansky, 22, of New York City, FBI agents agreed in writing to return clothing and a piece of shrapnel removed from Wilansky's arm during emergency surgery in November 2016.

Her father, Wayne Wilansky, consented to turn over the possessions to FBI agents without a warrant on the conditions that the agents sign an agreement to return the items "in a timely manner, so she could have them analyzed to determine the cause of her injury," the complaint said.

But the lawsuit describes futile efforts over the past 14 months to retrieve the property, and the nature of the FBI's investigation remains unclear.

An FBI spokesman declined to comment on pending litigation.

Sophia Wilansky of New York was airlifted to HCMC after being severely injured in the Dakota Access pipeline protest on Sunday.

Wilansky was one of thousands of "water protectors" who flocked to the Oceti Sakowin encampment to protest the construction of the Dakota Access pipeline. Early one morning outside a barricade erected by law enforcement, Wilansky was allegedly struck by a projectile that exploded, causing grisly injuries that left most of her left forearm missing.

In the months after the FBI seized the shrapnel and clothing, Wayne Wilansky made multiple calls to Assistant North Dakota U.S. Attorney Gary Lee Delorme to discuss the property. According to the lawsuit, Wilansky also proposed that the FBI allow a forensic chemist to analyze the material for the family.

According to the suit, Delormer told Wayne Wilansky in September 2017 that the government was in the process of retaining a metallurgist to examine the shrapnel for its investigation but did not describe the nature of the investigation or when it may conclude.

However, the complaint said that government documents described the FBI receiving test results on those same items from its laboratory just two weeks after it confiscated the evidence. Attorneys for Wilansky believe that the tests were "destructive" in nature, and "degraded and permanently altered the clothing and shrapnel."

The government also empaneled a grand jury within weeks of Sophia Wilansky's injury. However, the complaint said, the grand jury withdrew a subpoena before hearing testimony from a person who transported Wilansky to seek medical attention after the explosion, and has not subpoenaed further testimony or documents since. The government has not charged or arrested anyone in connection with the injury and no such case is "imminent or reasonably foreseeable," according to the complaint.

"This lack of information is a constant source of suffering for Sophia," wrote Matthew Pelikan, an attorney for Wilansky. "It prevents her from obtaining mental and emotional closure on an extremely painful event."