Constantine III reigns for eighteen months, according to the Chronicle of the Kings of Alba.

The Annals of Tigernach report that he was killed in a battle between the Scots in 997.

The Chronicle at Rathinveramond places his death at the mouth of the Almond where it meets the River Tay near Perth.

This appears to have been a royal center, close to Scone and Forteviot, as Donald I (Domnall mac Ailpín) is said to have died there in 862.

Constantine's killer is named as Cináed mac Maíl Coluim ("Kenneth son of Malcolm"), probably in error for either Kenneth, son of Dub (Cináed mac Duib), who becomes king, anglicized as Kenneth III on Constantine's death, or perhaps for Malcolm, son of Kenneth II (Máel Coluim mac Cináeda).

Constantine is not known to have any descendants and he is the last of the line of Áed (Áed mac Cináeda) to have been king.