Mariana Yepez rose through the Los Angeles street food scene before building her own taco empire.
A native of Sonora, Mexico, Yepez and her husband worked hard at various food trucks and restaurants until 2018, when they launched a series of stands named after their daughter: Ricos Tacos Naomi.
Serving plenty of fatty cabeza and hot al pastor, it has grown to nearly a dozen locations from Long Beach to LA to the Antelope Valley, to the acclaim of renowned food critics.
But now, Yepez is in prison – accused of conspiring to kill one of his employees.
Yepez, 43, and Ricos Tacos employee Naomi are charged with conspiracy to commit murder in the death of Soledad Lopez, who was last seen alive around 2 p.m. on September 7. A second employee is charged with murder.
Video surveillance showed Lopez, 47, leaving work at one of the taco stands with his co-worker, Sandra Romo Diaz. The two then went to a warehouse related to the business, according to a November court filing.
Lopez never appeared in the building. Prosecutors said Diaz was seen leaving and returning to the warehouse with two gas cylinders. Diaz, according to prosecutors, then drove away in Lopez’s car. Two days later, Los Angeles police found Lopez’s charred body in the car, according to a coroner’s report.
Diaz, 52, was burned in the arm and stomach while trying to set the car on fire and was soon charged with Lopez’s murder, according to court documents and a criminal complaint.
The authorities say that this brutal murder started after Diaz, Lopez and Yepez were involved in a car accident and argued over the money they received in court.
Authorities are still unclear about Yepez’s alleged role in the plot, but the intervention of US Immigration and Customs Enforcement has hampered efforts to prosecute him and another man suspected of involvement in the murder. One defendant in the case was ordered removed by an immigration judge and left before the trial, while Yepez was detained by ICE as the Los Angeles Police Department closed.
Yepez has pleaded not guilty, and his attorney, Justin Rodriguez, said he “did nothing wrong.”
“He’s being released as a young man,” Rodriguez said. “I hope you will be relieved when this is all said and done.”
Diaz’s attorney, Matthew Barhoma, reiterated his client’s innocence — and blamed ICE for letting people they suspect of being the real killers get away with it.
“We are left to defend Sandra from a murder case while the people we believe actually committed this crime are out of reach,” he said in an email to The Times. “That is an injustice – not only to Sandra, but to the memory of Soledad Lopez, whose family deserves answers, not a proper prison.”
Taco empire, a crash and a check for $11,500
The taco stand where Lopez and Diaz worked together was in some ways the embodiment of the American dream.
Yepez and her husband, who is from Guatemala, started working out of one of Roy Choi’s Kogi BBQ trucks, serving short ribs that epitomize Korean-Mexican fusion in the city.
Ricos Tacos Naomi employees eat meat at one of the stand’s 11 locations around town.
(Genaro Molina/Los Angeles Times)
Building off the success of Ricos Tacos Naomi’s first location in Panorama City, Yepez and his partners gained a following despite a lack of precision. Two stands visited by Times reporters recently did not even have a sign showing the name of the business. Still, customers lined up all over LA County.
“There’s a new taco stand that’s quickly taking over Los Angeles,” wrote Memo Torres of LA Taco in the 2022 update.
But authorities believe there was a disagreement between Yepez and his employee who was killed, according to a prosecutor’s statement in court and a police report reviewed by The Times.
After reporting Lopez missing last September, Lopez’s daughter told an investigator that Yepez had been mistreating her mother at work, a police report said.
One of Yepez’s relatives then told Lopez’s daughter that her mother “went missing because she allegedly stole money from a business,” according to a police report.
The financial dispute allegedly stemmed from a car accident in January 2025. While Yepez was driving Diaz and Lopez home from work one night, their car ran a red light, according to Neama Rahmani, a former federal prosecutor turned lawyer for the three women in their hit-and-run case.
All three suffered “soft tissue” injuries, but Yepez refused to see a doctor so Rahmani said he should drop his case. Lopez received a check for about $11,500, according to Rahmani, and Diaz received about $10,000.
A month before she went missing, Lopez’s daughter said her mother gave Yepez her insurance check and asked him to cash it, according to a police report reviewed by The Times.
Rahmani said the funds earmarked for Lopez were deposited into Chase’s bank account on August 28. The check was endorsed by Yepez, according to Rahmani. Lopez, however, “did not pay the money,” the police report said.
Yepez’s lawyer denied that his client was at fault.
“Everything I have seen tends to show that he is innocent and not involved in any allegations,” said Rodriguez.
Police asked prosecutors in September to immediately charge Yepez in connection with Lopez’s murder, but the LA County district attorney’s office initially remanded the case for further investigation, according to a spokeswoman for the agency.
But while police continued to piece together the case, Yepez was arrested by federal immigration agents. And he wasn’t the only suspect in the case to be taken out of the LAPD’s immigration enforcement reach.
Removal order and ‘suspect’ arrested by ICE
Surveillance footage that captured Lopez and Diaz entering the warehouse used by Ricos Tacos Naomi also showed a third person accompanying them, according to a transcript of the November hearing, where prosecutors fought to lower Diaz’s bail.
Diaz’s attorney says the man was Oscar Villafranca, another taco stand employee.
According to Rahmani, the lawyer who represented the three women after the car crash, Villafranca and Diaz were dating.
During a November bail hearing, the prosecutor said Lopez and Diaz met “another man” at the warehouse where police believe the killings took place. But Villafranca was not named and the surveillance footage presented in court did not capture what happened inside the warehouse, according to the indictment. During the trial, the prosecution did not say whether Yepez was present the night of the incident.
Investigators believe Lopez died before the car was set on fire, but have not been able to determine the exact cause of death or who killed him, due to extensive fire damage to his body, according to the coroner’s report. His death was ruled a homicide.
Villafranca, who is originally from Honduran, left the US on September 21, two weeks after the murder, a spokesman for the Department of Homeland Security said. Villafranca was first ordered removed from the country by an immigration judge during the Biden administration in August 2024. It was unclear whether police knew of Villafranca’s alleged involvement in the Lopez assassination plot while he was out of the country.
The day after Villafranca left the country, immigration agents came to Yepez.
He was arrested on September 22, according to a DHS spokesman, who declined to answer questions about his arrest.
A top Los Angeles law enforcement official, who asked not to be identified to discuss the ongoing case, said Yepez had been identified as a “suspect” in the murder conspiracy investigation at the time. The official said this is “not the first time” ICE has detained a person who was the target of an LAPD investigation last year, making it more difficult for local authorities to investigate and prosecute alleged crimes. The official blamed confusion over California’s “sanctuary state” law, which limits cooperation between ICE and local police.
A DHS spokesman would not say whether ICE knew about Villafranca or Yepez’s alleged connection to Lopez’s death, or comment on the agents’ involvement in the conspiracy case.
“Under President Trump and [DHS] Secretary [Markwayne] “Mullin, if you break the law, you will face the consequences,” said the spokesman.
The district attorney’s office filed a conspiracy to kill Yepez and Villafranca in April, eight months after Yepez was apprehended by ICE and Villafranca left the US under threat of deportation. Villafranca’s alleged role in Lopez’s murder is unclear.
ICE returned Yepez to LA County custody on June 2, and he is still being held on $2 million bond pending the trial.
Yepez’s lawyer said his client will be released.
“We hope that when all the dust settles, it will be confirmed,” said Rodriguez. “He has the support of his family and the community, and we intend to prove that he is innocent, and we are taking every step in this direction as we speak.”
Prosecutors will seek to extradite Villafranca, according to a spokeswoman for the district attorney’s office, who would not say if prosecutors know where he is.
Lopez’s killing is not the first criminal investigation to be disrupted by ICE’s immigration enforcement blitz in Southern California.
At the beginning of this year, a Times investigation revealed that ICE fired the informant who had turned in two of his co-conspirators in a meth-trafficking case. Despite his testimony, federal prosecutors lost the case. A man is facing a long prison term for what authorities have called the biggest crime in American history he was deported to Ecuador late last year before his trial in Los Angeles.
While Los Angeles County Dist. He said. Nathan Hochman has been critical of ICE, himself he previously told The Times those who commit crimes on American soil must face the consequences of their actions in LA before their immigration status is resolved.
“I don’t want someone to be deported from this country until I judge him. And if his sentence is in prison or state prison, I want him to serve his sentence,” he said in an interview last year. “That’s the punishment they get for committing a crime in my state.”
