A Middle Georgia investigation that began nearly half a year ago led to 87 pounds of cocaine being seized and 15 arrests last week — with more to come.

Houston County deputies launched an investigation into cocaine and marijuana distribution in the county in November, the sheriff’s office said in a news release.

Federal, state and other local agencies joined the investigation by February, when the scope of the operation was better known. By that point, the sheriff’s office knew it was dealing with a “large-scale” drug trafficking network, the release said.

On March 4, authorities seized a shipment of 39 kilograms (about 87 pounds) of cocaine, which has an estimated street value of $3.8 million, the release said.

The investigation also led to its first three arrests.

Dexter Lee Williams, 51, and Curtis Eugene Thorpe, 47, both of Macon, were arrested in Bibb County, while Francisco Daniel Costilla, 30, of Edinburg, Texas, was taken into custody in Baldwin County.

Costilla was driving a tractor-trailer when he was pulled over by authorities. He’s accused of hiding $284,600 in cash in a secret compartment inside the truck, which was seized during his arrest.

The next day, authorities executed search warrants at three locations in Bibb County, leading to more arrests and seized drugs, cash and firearms.

Twelve more suspects were taken into custody, while arrest warrants were obtained for four more.

Here are the names of the other suspects arrested in the investigation:

• Loretta McLan Williams, 51, of Macon;

• Kelton Keshawn Mims, 39, of Eastman;

• Oliver Oneal King, 50, of Tucker;

• Sirad Little, 46, of Perry;

• Donovan Jamal Williams, 37, of Macon;

• Joe Ben Sears Jr., 37, of Macon;

• Jonathan James Shaver, 30, of Perry;

• Christopher Anthony Burner, 46, of Forsyth;

• Lemark Williams, 47, of Macon;

• Darien Cantrell Harris, 38, of Thomaston;

• Christopher Thompson, 46, of Lithonia;

• Benjamin Maurice Kendall, 39, of Macon.

Everyone arrested was charged with violating the Georgia Racketeering Influenced Corruption Organization Act (RICO). The names of the four outstanding suspects with active arrest warrants were not provided.

The suspects all remain in the Houston County jail without bond. Their mug shots were not immediately available.

The FBI, Georgia Department of Public Safety, Bibb County Sheriff’s Office, Baldwin County Sheriff’s Office and Perry police are assisting in the investigation.

Anyone with information on this investigation is asked to contact deputies at 478-542-2080.

In other news:

Police said three children, a teenager and a 22-year-old were killed in the crash.