When Diana asked to speak to the boys, Gary told her "later" and hung up. Diana's sister, who was with Diana at the time, immediately called the police.
When police first arrived at Gary's house, they discovered that Gary had set up a makeshift bomb using two 400-pound (180 kg) propane tanks that would have exploded and destroyed both his home and the surrounding houses if anyone had tried to get inside. Diana believes that this was done in order to create a diversion.
In October 1997, almost a year after the disappearance, an engine assembly for a 1989 Ford Tempo, which may have been from Gary's vehicle, was discovered in the ocean near Flatrock, 10 kilometres from where the boys disappeared. No bodies were recovered from that location. Diana suspects that Gary dumped the engine of his car over the cliffs and into the ocean in order to deliberately mislead police.
The following year, police in Thunder Bay, Ontario received an anonymous tip from a woman who stated that she'd recognized pictures of the brothers. The woman said that she'd babysat for them, and knew the nicknames of one of the boys. Police attempted to locate the woman until 1999, but were unsuccessful.
Although Gary's sister suspects that her brother and her nephews are dead, Diana firmly believes that her sons are still alive, stating that Gary may have taken them to a religious commune and raised them in an environment with no access to technology or the outside world.
In order to aid the search for the O'Brien brothers, the National Centre for Missing and Exploited Children has created multiple age-progressed photos of the boys over the past two decades, with the most recent ones having been released in early 2017.
Gary O'Brien is wanted by Interpol for their abduction.
This case remains open.
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