Just a quick heads up before we get started.

Today's episode discusses images of child sexual abuse

and how they are detected online.

Okay, here's the show.

This story starts with the stay-at-home dad of a toddler

in San Francisco, a dad named Mark.

And in February 2021, his son developed a pain

in his penis that was red, a little swollen,

and Mark was worried about it.

That's reporter Kashmir Hill.

She covers technology and privacy for the New York Times.

Kashmir recently wrote about Mark and what happened to him.

He grabbed his Android smartphone and took a few photos

for the doctor.

Mark and his wife called the doctor's office

and scheduled an emergency appointment for the next morning.

And the nurse said, send the photos to us

so that the doctor can take a look before you guys meet

and try to diagnose what's going on here.

This was February of 2021, and because of the pandemic,

no one wanted to meet in person for any longer

than was absolutely necessary.

...