EL PASO COUNTY, Colo. — Eight arrests were made in Colorado Springs on Thursday as investigators from the El Paso County Sheriff’s Office conducted an operation related to the double homicide of Natalie Partida and Derek Greer.

There are 15 people now in custody as part of the investigation, the sheriff’s office said. Thursday’s operation took place in the 600 block of Yellowstone Road.

“As a result, 10 individuals were contacted and eight were arrested on various charges to include pre-existing arrest warrants and felony narcotics unrelated to the double homicide,” the sheriff’s office said in a statement. “All parties were taken into custody and booked into the Criminal Justice Center.”

Those arrested were Codey Slape, 25, Jonathan Briggs, 37, Justin Martinez, 29, Kristina Meyer, 38, Marsha Haughton, 25, Chase Girard, 29, Rhonda Keller, 54, and Amanda Allen, 27.

The bodies of Derek Greer, 15, and Natalie Partida, 16, were found on a road near Fountain on March 12.

The sheriff’s office says the investigation into their deaths is ongoing and additional arrests are expected.

The first suspect arrested, Gustavo Marquez, made his first appearance in court Tuesday to face formal murder and kidnapping charges. On Saturday, the sheriff’s office announced it had arrested Diego Chacon, 18, Joseph Arthur Rodriquez, 18, Marco Antonio Garcia-Bravo, 20, and Alexandra Marie Romero, 20.

On Tuesday, it announced Alander Jordan Wilson, 43, was taken into custody and on Wednesday, it was announced Angelita Prado, 21, was arrested.

Investigators also said they are looking for Carlos Meza, who is also known as “Tink,” and Endo Velarde, 17.