Duff (a.k.a. Duffus; Dub mac Maíl Choluim; or Dubh) lived from 930 to 966 and was King of Alba from 962 to 966. The wider picture in Scotland at the time is set out in our Historical Timeline.
The abiding problem faced by Duff during his reign was the challenge of Culen, King Indulf's son. Culen was not prepared to accept the succession arrived at by the law of tanistry and felt that as Indulf's son, the crown should have come directly to him. Following the battle, Duff fell seriously ill and the affairs of state fell into disrepair and rebellions started in a number of areas.
But he recovered, and sought to regain his authority with campaigns in Moray and Ross, culminating with a victorious battle at Forres in 966. Leaders of the rebellions were brought to Forres for execution. Those executed included kinsmen of the governor of Forres Castle. In revenge, the governor arranged for Duff's guards to be drugged and for Duff to be kidnapped and then murdered. The murderers diverted a stream from its course under a bridge at Kinloss and buried his body under the stream bed and under the bridge, before allowing the stream to resume its normal course.
It has been suggested that the magnificent 20ft tall Sueno's Stone which stands on the north east side of Forres may depict Duff's victory in 966, and his subsequent murder and burial under the nearby bridge: though it has to be said that many other interpretations have also been suggested for the carvings on the stone.
Duff's body was recovered from its hiding place and reburied in the graveyard at Saint Oran's Chapel on the Isle of Iona. Duff was succeeded by Culen, who most Scots at the time believed to have been behind Duff's death: and who may indeed have been involved.