LOS ANGELES (CNS) — An 18-year-old woman charged along with three reputed gang members in the fatal shooting of an off-duty Los Angeles Police Department officer was ordered held without bail Tuesday.

Federal authorities said Haylee Marie Grisham is the girlfriend of one of the co-defendants charged in the killing of 27-year-old Officer Fernando Arroyos, who was shot during a robbery at 9:15 p.m. Jan. 10 in the 8700 block of Beach Street in the unincorporated Florence-Firestone neighborhood.

Authorities said Arroyos was targeted while he was house-hunting with his girlfriend.

Grisham appeared Tuesday for her initial federal court appearance in downtown Los Angeles where the judge ordered that she remain in custody. She was set to be arraigned on Feb. 7, according to the U.S. Attorney's Office.

Grisham was charged Thursday along with Jesse "Skinny Jack" Contreras, 34; Luis Alfredo "Lil J" De La Rosa Rios, 29; and Ernesto "Gonzo" Cisneros, 22. Grisham is Rios' girlfriend, authorities said.

All four defendants were charged with violent crime in aid of racketeering to increase and maintain position within the Florencia 13 gang. The charge carries a potential death penalty and a minimum sentence of life in federal prison without the possibility of parole because the fatal shooting occurred during a robbery, according to the U.S. Attorney's Office.

Contreras and Rios made their initial appearances in downtown Los Angeles federal court Friday, and they were ordered to remain jailed without bail, with arraignment tentatively set for Feb. 3. A court date has not yet been set for Cisneros, who authorities say was wounded in an exchange of gunfire with Arroyos during the robbery.

According to a sworn affidavit from an FBI agent, Rios admitted in an interview with sheriff's detectives his involvement in the killing, saying he and the other defendants were driving around looking to "make money" by robbing someone.

The complaint alleges that Rios and Cisneros exited a black pickup and confronted Arroyos, a three-year veteran of the LAPD, and his girlfriend as they were searching for a home to purchase in the area.

The two allegedly pointed guns at the victims and removed property from both, including a wallet and two silver chains from Arroyos' neck, according to Capt. Joe Mendoza of the Los Angeles County Sheriff's Department.

"At some point after Cisneros removed (Arroyos') chains, (Arroyos) and the two suspects exchanged gunfire," according to the criminal complaint.

Arroyos sustained a single gunshot wound, ran from the area and collapsed in an alley as the two suspects fled the scene in the truck.

Responding sheriff's deputies arrived at the scene and found bystanders performing CPR on Arroyos, Mendoza said. The deputies loaded Arroyos into a patrol car and took him to a hospital, where he was pronounced dead.

Detectives retrieved a loaded handgun from the scene belonging to one of the suspects, and the sheriff's department received a report at about 9:25 p.m. of a man suffering a gunshot wound in the area of Junction Street and East 60th Street, about a mile-and-a-half from the site of the shooting, Mendoza said.

Investigators later determined the wounded man was Cisneros, who was shot during the exchange with Arroyos. Contreras was also found in the area, hiding inside the garage of his residence in the 5900 block of Junction Street.

A second handgun was retrieved from Contreras' residence and will be tested to determine if it was used in the shooting, Mendoza said.

Rios and Grisham were later found and taken into custody at their residence.

Los Angeles County Sheriff Alex Villanueva, whose agency handled the shooting investigation, said Thursday night he directed detectives to take the case to the U.S. Attorney's Office because of his opposition to District Attorney George Gascon's decision to no longer pursue sentencing enhancements in gang cases. 

Those enhancements in a murder case can mean the difference between a possibility of parole and never being released from prison.

Villanueva said a murder prosecution "with no gun enhancements, no gang enhancements, nothing ... really did not cover the depravity of this crime. It should be noted that the California penal code does cover all these things. The tools are there but we need to have someone who's willing to use them."

The Los Angeles Police Protective League, the union representing LAPD officers, issued a statement Friday applauding the sheriff's decision to seek federal prosecution, calling it a "complete repudiation of the dangerous policies and heartless treatment of crime victims exhibited by" Gascon.

The District Attorney's Office responded Friday, saying it supports the federal handling of the case and will "be in communication with all the parties involved.

"It was indicated to us that the case was referred to the federal authorities, who filed charges," according to the DA's Office. "As such, we did not have an opportunity to review the case."