A dad accused of killing his two children by leaving them in a hot truck has been released after CCTV showed them climbing into the vehicle themselves.

Dustin Dennis, 31, was arrested following the tragedy, which claimed the lives of daughter Teagan, four, and son Ryan, three.

However a neighbour’s camera showed the children climb into the truck but not coming out again.

Dennis, from Tulsa in Oklahoma, US, was arrested on suspicion of second degree murder, but has not been charged.

His bail was initially set at $750,000 before he was released.

Just two days before their deaths, he had written on a Facebook post that he couldn’t imagine the world without them.

The dad – who did not live with his children – told police he had taken them shopping on Saturday.

When he got home, he told detectives, he fell asleep for four or five hours – during which time the children climbed into the truck.

According to Fox 23, Dennis said he woke up and was unable to find his children, before discovering them on the floor in the vehicle.

He called 911, but sadly paramedics pronounced the two young children dead at the scene.

In a statement the Tulsa District Attorney’s Office said, the Daily Mail reports: “Video surveillance footage from a neighbor’s home confirmed that the children managed to get into the truck and tragically never got out.”

Officers had initially stated a neighbour filmed Dennis locking the vehicle without taking the children out.

Dennis had written on his Facebook page two days before their deaths about how much he loved them.

The dad wrote: “2 in the morning up watching my kids sleep, I can’t believe they’re mine, I love them so much and nobody in this world could ever make me feel as loved as they do.

“The other day I was so depressed because I just missed them, and I got to thinking of when they get older and become adults.

“If you don’t have kids you may not understand this but that is the scariest but most amazing thing to think of, watching them become their own person and seeing what they will experience and achieve.”

And the heartbreaking post continues: “I hope our bond only grows stronger, I hope they always want to call me or see me just to talk or ask for advice. I can’t imagine this world without them.”