Josh Powell's Chilling Final Message

Grim new details from the final hours of Josh Powell and his two young boys are coming to light. INSIDE EDITION has the final message he left behind before killing himself and sons.

A chilling final message from Josh Powell, obtained exclusively by ABC News, was left on a voicemail to his family just minutes before he blew up his house, killing himself and his two sons.    

"Hello, this is Josh. And I'm calling to say goodbye," Josh said on the message. "I am not able to live without my sons, and I am not able to go on anymore. I'm sorry to everyone I've hurt. Goodbye."

Now we're learning more details about his incomprehensible act of evil.

Both little boys suffered "chop injuries" from an ax—yes, an ax. Then, Powell used two five gallon cans of gas to blow up the house.

Josh Powell's sister Alina had an angry reaction when she was asked about the tragedy that has stunned the nation.

A reporter said, "I'm sorry for what you're going through."

"No you're not. You guys caused this. Goodbye," exclaimed Alina as she shut the gate in the reporters face.

We now know Powell carefully planned the murders. He even donated their toys at a Goodwill store.

Seattle detective Ed Troyer said, "This is definitely a deliberate, planned-out event."

The boys didn't want to visit their father but their grandparents, Chuck and Judy Cox insisted they go.  

Judy Cox showed INSIDE EDITION's Jim Moret their room, filled with toys and art projects. Her eyes filled with tears as she spoke of the loss of her daughter Susan and now her two grandsons, seven-year-old Charlie and five-year-old Braden.

"What I feel is the boys are with their mom now," said Judy.

In Braden and Charlie's bedroom, when they sat at their desk, a picture of their mom was never far away.

The last touching photos of Charlie and Braden show them horsing around with their granddad and snuggled in front of the fireplace with a photo of their mom, missing and presumed dead since 2009, in the background.  

Charlie posed in front of the photo because his granddad says he wanted his picture taken with his mom.

Moret spoke to Susan Powell's sister Denise, who remains shocked at the loss of her little nephews.

"When we found out the extent of how they went, it was unbelievable. He made them suffer and there was no reason for it," said Denise.