HONOLULU (AP) — A young monk seal found dead on the Hawaii island of Molokai last month had injuries that were intentionally caused, authorities said.

The body of the female seal, identified as RJ42, was discovered on the west end of Kawaaloa Bay on May 31.

The National Oceanic and Atmospheric Administration Fisheries conducted a post-mortem examination of the seal the next day, finding the injuries that caused the death were purposely inflicted by someone.

NOAA's Office of Law Enforcement is investigating the death. Authorities did not describe the nature of the injuries, citing the ongoing investigation.

The monk seal is believed to be the sixth killed by people since 2009, said Michelle Barbieri, a NOAA veterinarian. It's the third killed in Moomomi, the northwestern shore of Molokai.

The Hawaii monk seals are among the most endangered marine mammals, according to NOAA. About 1,400 seals were counted around the Hawaii islands in 2017.

"The monk seals that are killed in this way, unfortunately, impact recovery of these species because they are potentially females that would have grown up to give birth to pups of their own someday," Barbieri told Hawaii News Now. "So not only do we lose the life of this particular individual, but we do unfortunately lose the future reproductive output of those individuals."

NOAA asks people with information about the seal's death to contact the federal agency.