The mystery behind the 2013 murder of a pregnant woman in Hawaii has been solved, police say, after authorities found a note left behind by her boyfriend confessing to the killing before he hanged himself.

The body of Brittany-Jane Royal, 25, was discovered floating in the waters off Kalapana, Hawaii, on May 28, 2013, and authorities suspected that her boyfriend, 22-year-old Boaz Johnson, was behind the murder.

Royal, from California, and Johnson, from Alaska, were living at a campsite at the time. Johnson vanished after Royal was found dead.

His body was found on Jan. 2, Hawaii police revealed Tuesday at a news conference.

“A composition book was found near Johnson’s body,” Hawaii police said in a statement. “In three handwritten pages, the writer -- who identified himself as Boaz Johnson -- confessed to strangling Royal while involved in a domestic dispute and to throwing her body into the ocean.”

Johnson and the note were found about a mile and a half away from where Royal’s body was discovered, Hawaii News Now reports.

A forensic document examiner determined that the writing was Johnson’s, and the rope he used to hang himself was similar to the one used to strangle Royal, according to KHON2. DNA tests also proved that the man was Johnson.

Julie Royal, Brittany-Jane's mother, told the station that there is a “sense of relief” that the family finally knows who the killer is.

"She wanted to love and she wanted peace and she wanted to explore different cultures and know about different people,” Julie Royal said of her daughter. “She's doing that up in heaven."

The family plans to return to Hawaii in February to hold another memorial.