CONCORD — Sean Sweeney, the man whose wife and two young children were shot to death in their Northfield family home on Wednesday, is “beyond devastated” and being assisted by victim-witness professionals, a homicide prosecutor said Friday afternoon.

Homicide prosecutor Geoffrey Ward also said the shootings of Kassandra Sweeney, 25, Benjamin Sweeney, 4, and Mason Sweeney, 1, were not random.