After his father died in 656, Dagobert was ordered to be killed. However, he was spirited out of the country and raised in the Irish monastery of Slane. In 675 he was found with the effective help of Wilfrid, Bishop of York, and restored in 676.
He was murdered December 23, 679 on orders from Pepin "The Fat" near Stenay in Lorraine.
The idea that he married a so-called "Giselle De Razes" appears to be a complete fabrication. There is no primary evidence for such a person or such a marriage.
Even the idea that this restored "Dagobert" was actually the same as the child-heir to the throne of Austrasia is questionable. Wilfrid, who had had his own problems with getting his appointment to York effected, certainly could have had ulterior motives in promoting a claimant to the throne of Austrasia. He had been resident at Lyons for three years, sometime between 650 and 664, when his sponsor was murdered, so there was no love lost between him and Frankish politics. He was also resident there at the time of the murder of Dagobert II, December 23, 679.