By Melissa Garcia

COLORADO SPRINGS, Colo. (CBS4) – Authorities have arrested four additional suspects in connection with the killing of two Colorado Springs teenagers.

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(credit: CBS)

A passerby found Derek Greer, 15, and Natalie Partida, 16, dead on the side of a road near Fountain earlier this month.

Derek Greer, 15, and Natalie Partida, 16 (credit: El Paso County)

Those who knew them say that Greer and Partida were best friends. Both were students at Coronado High School.

El Paso County Sheriff’s deputies arrested these four suspects Friday and into Saturday morning in Colorado Springs:

Diego Carlos Chacon (credit: El Paso County)

Joseph Arthur Rodriquez (credit: El Paso County)

Marco Antonio Garcia-Bravo (credit: El Paso County)

Diego “Casper” Chacon, 18, Joseph Arthur Rodriquez, 18, and Marco Antonio Garcia-Bravo, 20, are charged with two counts of first degree murder, two counts of second degree kidnapping, aggravated robbery and child abuse.

Alexandra Marie Romero Diego Carlos Chacon (credit: El Paso County)

Alexandra Marie Romero, 20, is charged with second degree kidnapping and accessory.

A SWAT team honed in on a residential area near Union Boulevard and Constitution Avenue Friday in the arrest of Chacon.

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Deputies made the arrests with the help of the Colorado Springs Tactical Dispatch Unit.

Authorities arrested a fifth suspect, Gustavo Marquez, 19, earlier this week.

Gustavo Marquez (credit: El Paso County Sheriff’s Office)

Jacqueline Kirby, a spokesperson for the El Paso County Sheriff’s Office, said that she could not reveal details behind how the murders happened or what led up to the arrests.

“Since the investigation is still ongoing, I don’t want to give away some of the tactics we used, the investigative tools that assisted us, only because there still may be additional arrests forthcoming,” Kirby told CBS4’s Melissa Garcia in a phone interview.

Kirby could not comment on a motive, but did say that the victims knew some of the suspects.

She said the agency was working hard to bring justice to the victims’ families.

“I can’t imagine what the parents are going through,” Kirby said. “And we will continue to honor Derek and Natalie and bring justice to their families.”

Greer’s mother said earlier this week she is devastated by her son’s death.

All five suspects were behind bars at the Criminal Justice Center in Colorado Springs.

Advisement hearings for the latest four arrestees were expected to happen Monday.

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Melissa Garcia has been reporting for CBS4 News since March 2014. Find her bio here, follow her on Twitter @MelissaGarciaTV, or send your story idea to mkgarcia@cbs.com.