Three men and a woman — all charged with capital murder — lured men to their deaths in a robbery scheme involving prostitution this month, Dallas police say.

They're also responsible for killing a woman who refused to take part in their plan, according to WFAA-TV (Channel 8).

Joy Tiara Gray, 21; Kevin Wayne Kidd, 28; Emmanuel Lewis Kilpatrick, 30; and Jermon Antwon Simmons, 34, are being held at the Dallas County Jail.

From left: Joy Tiara Gray, Kevin Wayne Kidd, Emmanuel Lewis Kilpatrick and Jermon Antwon Simmons (Dallas Police Department)

In all, four people were killed in a spree that lasted several days in mid-March, police said.

The first was a woman whom the men reportedly tried to force into working for them as a prostitute. According to WFAA's report, Kidd admitted to police that he and Kilpatrick forced her into their car at gunpoint.

Kilpatrick shot her multiple times when she wouldn't take part in the scheme, WFAA reported.

Police have not released the woman's name, but the television station says authorities have video footage of Kidd and Kilpatrick's vehicle, as well as a second vehicle driven by Simmons, going to and from the place she was killed.

Gray, who was arrested over an unpaid ticket March 17, told police that a week earlier she had agreed to have sex for money with Irby Walton Sr., 69, at his east Oak Cliff apartment, WFAA reported. Police found evidence on Walton's cellphone that that two had communicated.

Irby Walton Sr. ((Dallas Police Department))

Walton's son, 41-year-old Irby Walton Jr., was at the home in the 3100 block of Simpson Stuart Road when they arrived around 11:30 p.m. March 10.

Witnesses told police that they had seen the elder Walton go into the apartment with a woman and that they heard gunshots later. They saw three men and a woman leave the apartment, according to an arrest warrant affidavit. One witness also saw the men taking a large television.

Irby Walton Jr. ((Dallas Police Department))

Gray admitted to police that she had texted one of the men about the electronics and other items inside the apartment, according to the affidavit. She also identified Kidd, Kilpatrick and Simmons — her boyfriend — as the men in question.

Kidd, arrested March 20, told police that he helped Simmons take two televisions and an Xbox from the apartment, the affidavit says. When he went inside, he saw two men on the floor with their hands tied behind their backs. Kilpatrick was asking the men where the money and the key to the safe were, Kidd told police.

Kidd said he saw Gray and Simmons leave the apartment, but not Kilpatrick, according to the affidavit.

Simmons told police that he had helped take a 65-inch television and a PlayStation 4 from the apartment, and that Kilpatrick had a pistol, according to his arrest warrant affidavit. He said he later threw the PlayStation into the Trinity River.

Kilpatrick, in his interview with detectives, said that Simmons had a gun during the robbery and that he heard gunshots from the apartment as he was leaving. He said Simmons told him later that he had to shoot Irby Walton Jr. because he was getting loose from his restraints, according to his arrest warrant affidavit.

Police found the Waltons about 10:30 the next morning. One of the televisions was found at Kidd's home, and a vehicle belonging to Irby Walton Jr. was found burned in the 4700 block of Great Trinity Forest Way.

Less than 48 hours after Gray first encountered the Waltons, she met up with 53-year-old Cristobal Zepeda, according to an arrest warrant affidavit.

They went to an ATM around 6:30 p.m. March 12 and then drove around in Zepeda's car for about an hour to find somewhere to park. Meanwhile, Gray was letting Kilpatrick know where they were, the affidavit says.

Cristobal Zepeda (Green Funeral Home)

After Zepeda drove to the 500 block of Pontiac Avenue, Kilpatrick and Simmons arrived and blocked in Zepeda's vehicle, the affidavit says. After Gray got out of the car and the men tried to rob him, Zepeda attempted to drive off, authorities said.

Kilpatrick shot at least twice at Zepeda, hitting him once in the head, according to the affidavit.

Zepeda's car crashed through the gate of a food-recycling plant and struck a pickup; an employee found him around 5:15 a.m. the next day.

Gray told police that she had agreed to help the men with the robbery but did not plan on Zepeda being killed, the affidavit says. She also drew detectives a diagram of the crime scene.

Simmons told police that he had driven Kilpatrick to the location and that Kilpatrick shot Zepeda, according to the affidavit.

Police found a gun at Kilpatrick's home and are testing to see whether it's a match to a weapon used in the slayings, according to WFAA's report.

Police said the investigation is ongoing and would not comment further.

Gray, Kidd, Kilpatrick and Simmons have each been charged with one count of capital murder. Gray also faces a charge of aggravated robbery, and Kilpatrick has been charged with aggravated assault with a deadly weapon.

Bail has been set at $1 million for Simmons, $525,000 each for Gray and Kilpatrick and $500,000 for Kidd.

Each of the four has multiple previous convictions: Gray for prostitution and criminal trespass; Kidd for aggravated robbery, drug possession, evading arrest and failure to ID; Kilpatrick for aggravated robbery, burglary and unlawful possession of a weapon; and Simmons for murder, attempted robbery, drug possession, evading arrest and failure to ID.

Staff writers Claire Z. Cardona and Naheed Rajwani contributed to this report.