Arrest Made in 'Sextortion' Case That Caused 17-Year-Old's Suicide

San Jose police have made an arrest months after a teenage boy took his life -- this after being extorted for money when he sent a nude photo to someone he thought was a teen girl.

SJPD announced Monday 25-year-old Jonathan Kassi was taken into custody in Los Angeles to face charges of extortion and attempted disorderly conduct ... related to posting a photograph or recording without consent.

The cops are saying Kassi is connected to the death of 17-year-old Ryan Last -- who died by suicide in May when someone he'd been chatting with online demanded he send them $5,000 upon receiving an intimate picture they'd solicited from him or else the pics would go public.

Ryan apparently believed he was communicating with a girl his age -- and when a photo was sent to him that person asked for a similar naked photo in return, which he sent.

Once the fraudster got the photo of Ryan ... he demanded money on the threat of releasing the picture publicly among his friends and family members. Ryan didn't have anywhere near $5,000 but he did pay $150. It was at this point Ryan panicked and died by suicide.

Amid their investigation -- which ended up including the FBI -- law enforcement said they believed this was happening on a larger scale ... where crooks from overseas were tricking young people into sending compromising material, and then extorting them for quick cash.

The San Jose Crimes Against Children Task Force said they were looking into possible ties to a West African financial extortion scheme ... which could also connect to Southeast Asia.

The cops, thus far, have stopped short of explicitly connecting Kassi to any greater criminal enterprise -- but we're sure more info is due to be released as the process plays out. They're saying they suspect Kassi might've victimized other minors as well through multiple profiles.

The same day Kassi was arrested, the FBI and Dept. of Homeland Security issued a PSA about this phenomenon -- saying it was happening all across the country (mostly to boys) and that it had resulted in more than a dozen suicides. Scary stuff, to say the least.