Calgary detectives have travelled to Mexico as part of their investigation into the disappearance and murder of a five-year-old boy and his grandparents, CTV News has confirmed.

Nathan O’Brien and his grandparents, Kathy and Alvin Liknes, went missing on June 29. Police believe they were murdered, although their bodies have not been found.

The Liknes couple had been planning to relocate to Mexico before they disappeared. Detectives are now working with police in Mexico.

Nathan was at his grandparents’ home for a sleepover when all three family members went missing. Police have said that there were signs of a violent struggle inside the Liknes home.

Despite exhaustive searches of municipal dumps and a rural property near Airdrie, Alta., police have not been able to find the victims’ bodies.

Douglas Garland, 54, has been charged with two counts of first-degree murder and one charge of second-degree murder in the case.