Virginia authorities are dealing with two MS-13 gang-related murders they believe are connected, and it involves those three missing teen cases we reported on much of last week.

Thursday, a Prince William County Police spokesperson also confirmed a 21-year-old male killed had been lured to a location online.

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The 21-year-old murdered is Christian Alexander Sosa Rivas, whose body was discovered in Dumfries on January 12th. Police are also dealing with the murder of Damaris Alexandra Reyes Rivas, the 15-year-old from Gaithersburg who went missing and was found dead in Springfield, Va. a couple weekends ago.

Many suspects are in custody but investigators are also connecting one person WUSA9 spoke to, to the two homicides.

WUSA9 was at her home just moments before 17-year-old Venus Iraheta returned. She had been missing for nearly a month. Police put out a public, desperate plea for her return, fearing her disappearance was connected to two other missing teenager cases in the DMV, one of which ended in a homicide.

Her mother thought Iraheta was dead.

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The 17-year-old told us on camera, “The reason why I left was because I was scared about to my ex-boyfriend."

That ex-boyfriend, WUSA9 learned, is Christian Sosa Rivas, the 21-year-old whose body was found on January 12th near the shore of the Potomac River in Dumfries, Prince William County.

Authorities say he and 15-year-old Reyes, the teenager found dead in Springfield, Va., were dating.

WUSA9 asked Iraheta if she knew what happened to Reyes.

"I just heard about it … I'm not really,” Iraheta said.

Now we're learning that's not entirely true. Sources told WUSA9 reporter Peggy Fox, the 17-year-old played a gruesome role in Reyes' death and that Reyes wasn't exactly innocent either.

These are two large and complicated MS-13 gang-related murder investigations that stretch multiple states. Fairfax County Police already have 10 suspects in custody for Reyes’ murder. Thursday, Prince William County Police announced five arrests for Sosa's murder.

These alleged gang members were picked up in Baltimore and Pennsylvania.

The cases overlap, many of the suspects are teenagers or very young adults.

"It's amazing to me that someone so young can be involved in the things that they're alleged to be involved with,” said Prince William County Commonwealth's Attorney Paul Ebert on Thursday.

It’s a warning for parents about their children’s social media activity online. Prince William County Police would not confirm details due to the investigation but say in Sosa’s case, online luring is involved.

WUSA9 recently reported on another MS13-related murder in Montgomery County, Md. that involved gang members using Facebook to pose as others and lure a New Jersey man to his death.

WUSA9 asked Montgomery County Police about gang activity in county schools since just last week, the head of the Northern Virginia Regional Gang Task Force told WUSA9 recruiting in the Northern Virginia area is being seen as early as 5th grade.

MCP Captain Paul Starks said over the phone, social media plays a huge role. He described social media as allowing young, vulnerable kids to connect with people they are familiar with. Unfortunately some of those people could be gang members.

Reyes’ mother interviewed last week pleading for parents keep a close eye on their children’s friends, realizing her own daughter’s connection to MS-13 gang members.

Fox says according to sources, Sosa had been posing as a MS-13 gang leader. No motive has been announced yet in any of the two cases.