Allen Engstrom posted this photo on Facebook. Engstrom's iPad is missing and he believe this woman may have it. (Facebook/Allen Engstrom)

A U.S. man has been sharing with the world funny photos of the woman who has his missing iPad.

Allen Engstrom told ABC News he left the device on a plane while travelling from Phoenix to Denver.

A month later, his son held up another Apple device, showing a picture of a woman making a funny face and said: "Mommy, what's this?"

Engstrom's iPad automatically backs up pictures to his iCloud service. The woman in the picture has Engstrom's iPad.

Engstrom's not the first person to share shots of an alleged computer thief. This Guy Has My Macbook has long been a popular blog.

But the person in the pictures isn't always the thief.

In 2008, an Ohio teacher posted naked pictures of herself on a stolen laptop. A theft recovery company tracked her down and she was arrested.

But it turned out she bought the computer second-hand, and later sued the police and the company.