North Carolina authorities say a teenager charged with killing his grandfather with a hatchet discussed the crime in advance with a still-unidentified person on a cellphone communications app.

The Fayetteville Observer reported (http://bit.ly/2gVO9Bl ) that according to a detective's affidavit for a search warrant the teen discussed his forming plans before attacking 63-year-old Joseph Emmett Naulty in August.

The affidavit said the boy discussed in his cellphone messages that he found the grandfather who recently moved into his home, "just kinda inconvenient."

Sheriff's department spokesman Sgt. Sean Swain said detectives are working with the Canada-based company behind the app called Kik to identify the person messaging with the Cumberland County teen.

The 16-year-old is charged as a juvenile with first-degree murder. Prosecutors are deciding whether to try him as an adult.