A little boy's testimony led Spanish police to the bodies of his mother and 10-year-old brother in a cave on the island of Tenerife.
Police arrested the father, suspected of killing the two victims.
Locals alerted police after finding the distressed five-year-old boy wandering in the mountains near Adeje, muddy and crying, on Tuesday 23rd April.
Spanish media say the mother and boys had arrived to see the father on Monday. The family are all German and he is a resident on Tenerife.
The father was arrested at his apartment, reportedly after a struggle.