What an iDiot!

A Manhattan woman led cops to the dummy who stole her iPhone after the clueless crook used it to take pictures of himself and send them via her e-mail, police sources said yesterday.

“There he is. Isn’t he stupid?” victim Sayaka Fukuda, 29, wrote on her blog next to the photo of Daquan Mathis, whom cops busted for the robbery.

Fukuda, a shoe designer who immigrated from Tokyo three years ago, was on the N train platform at the Fifth Avenue station near 59th Street at 4:30 a.m. on Feb. 21 when the robbery took place.

“It was a scary night,” she told The Post. “It was stupid that I took the train that late.”

Mathis, who was with an accomplice, came up and grabbed the phone from her, she said. After a struggle, he allegedly threw her purse onto a train and got on, she said.

“I kept screaming. ‘No! No! No!’ ” Fukuda recalled.

She reported the theft to cops, went home and got the surprise of her life.

“I checked my e-mail and saw something in my outbox,” she wrote on the Japanese-language blog. “I knew I didn’t send anything.

“I opened the attachment, and there he was with his black and red knitted [Spider-Man] hat. The same hat I described to the police officers.”

She sent the photos off to cops who combed through mug shots and quickly zeroed in on Mathis, 18.

He had sent the pictures to his own e-mail account, the sources said.

Meanwhile, Fukuda began a correspondence with the man who allegedly robbed her.

She e-mailed him, “Thank you for your picture. I sent them to the cops, you’re going to get arrested soon,” according to the blog.

She said he e-mailed back the next day, “I will kill you! I know where you live, I know where you work. I’ll send people.”

Fukuda said, “When I read this, I was crying and shaking. But I wrote him back anyway,”

Despite the alleged threat, she begged him to do the right thing, writing, “Don’t ruin your life for a cellphone. Go to the cops before it gets worse.”

The thief wrote back, “You’re right, but I’m not going to the cops.”

Mathis was busted Thursday and charged with robbery and grand larceny.

After his arrest, Mathis confessed to two other crimes including another robbery on an N train in which he stole an iPod at gunpoint, police sources said.

Mathis’ stepfather, Sterling Wade, said police came to his house several times over the last two weeks looking for him.

“They said he was wanted for armed robbery,” he said.

Additional reporting by Jennifer Fermino, Ed Robinson and David Greene

jamie.schram@nypost.com