A bald eagle that was pulled from the icy Hudson River in February by NYPD officers has died.

Officers from the NYPD’s Harbor Unit saw the bird floating on the ice while on patrol just north of the George Washington Bridge on Feb. 17. After hearing it call out, the unit moved in to help, pulling the eagle from the frigid water.

The eagle was taken to the Raptor Trust, a nonprofit rehab facility for birds of prey in Millington, N.J.

“The bird was in critical condition when it arrived. We were able to stabilize its condition and perform a series of diagnostics, which found dangerously high levels of copper in its system,” the Raptor Trust said on social media.

Officials from the Raptor Trust say copper toxicity is very difficult to treat. Volunteers attempted a procedure called chelation, which can often remove heavy metals from the system, but despite showing some initial signs of improvement, the bald eagle did not fully respond to the treatment.

In March, the eagle began to show some signs of improvement. The elevated liver numbers had started to decrease, and the eagle was becoming more alert. In the weeks that followed, however, its condition deteriorated and it died on April 18.

Officials at the rehab facility said the eagle was 18 years old and was banded as a juvenile in Stony Point, N.Y., in 2008.

“It was known to have nested successfully for at least 10 years along the Hudson River,” the Raptor Trust said. The eagle’s remains will be sent to the New York State Department of Environmental Conservation, where additional testing will be performed.