San Antonio police arrest stepmother of man accused of killing pregnant teen and her boyfriend

A third person was arrested Wednesday in the deaths last month of a pregnant teenager and her boyfriend in what San Antonio police have said appeared to be a botched drug deal.

Myrta Romanos, who police say is the stepmother of the alleged killer, is accused of altering, destroying or concealing a human corpse, abuse of a corpse and tampering with evidence, Lt. Michelle Ramos said.

Christopher Preciado, 19, has been charged with capital murder in last month's deaths. Preciado’s father, Ramon Preciado, 53, was charged with abuse of a corpse.

Romanos, 47, who was in handcuffs, ignored a hail of questions from reporters about her possible involvement Wednesday afternoon as she was escorted into a police car. Police earlier Wednesday provided a different spelling for Romanos.

It was not immediately clear whether she had secured an attorney who could comment on her behalf.

In addition to capital murder, Christopher Preciado is also accused of abuse of a corpse and altering, destroying or concealing a human corpse, according to court records. Ramon Preciado is also charged with aggravated assault with a deadly weapon, evading arrest and altering, destroying or concealing a human corpse, court records show.

Savanah Soto, 18, and Matthew Guerra, 22, were found dead in Guerra's Kia Optima the day after Christmas in a parking lot of an apartment complex, police said.

They had been shot in the head, authorities said. Leon Valley police said that when Soto disappeared, she was past her delivery date and that her family had contacted San Antonio police because she missed “an essential medical appointment.”

Police said that detectives had been seeking a third suspect since the earlier arrests but that officials waited to make the third arrest until they could collect the proper evidence and present the best case to prosecutors, said Ramos, the police lieutenant.

Security video shows that Romanos was "involved the night of the murder," Ramos said.

Security camera video police released after the bodies were found showed a heavy-set person driving a dark Chevrolet Silverado and another driving Guerra’s Kia. The two appeared to speak to each other out of the vehicles before driving away in separate directions.

Romanos admitted that the gun used in the slayings belonged to her, police said.

"We're confident that there are no more suspects," Ramos said.

Police spoke with relatives of Soto and Guerra after their bodies were found. According to an affidavit for an arrest warrant, investigators learned Guerra sold drugs and would post money and drugs on Instagram.

According to the affidavit, Ramon Preciado was seen on security video and admitted driving his Silverado, which was also seen on the video, near where the Optima was found.

He also allegedly said he met his son, who was driving Guerra’s Optima at the apartment complex, where it was later found.

Christopher Preciado told police that Guerra and Soto drove to his house, a few blocks from where the Optima was discovered, to sell him marijuana. His statements then were inconsistent with collected evidence, the affidavit said.

“Christopher claimed the male victim pointed a weapon at him and Christopher was able to manipulate the weapon resulting in the female being shot,” according to the affidavit. “Christopher then stated that ... the weapon pointed at him again and he manipulated the weapon again resulting in the male victim being shot.”

Police said Wednesday that Romanos was seen on security video leaving her home shortly after the slayings.

Police spoke with Romanos, who said she thought she was sleeping on the night Soto and Guerra were killed, according to an affidavit for an arrest warrant obtained by NBC News.

A gun was found in a closet in Romanos' bedroom, the affidavit said, noting that she said the gun was hers. The gun forensically matched the shell casing found in the victims' car, according to the affidavit.

In addition, the affidavit said, security video of the Silverado near the scene of the crime appeared to show a second person in the vehicle throwing a towel to Ramon Preciado, who used it to wipe off the Optima's door where he had touched it.

Security video from the suspects' home also showed Romanos leaving the residence with Ramon Preciado, the affidavit said.

"Several minutes later, Ramon's vehicle entered the driveway of their residence. Christopher, Ramon and Myrta could all be observed exiting the vehicle," according to the affidavit.

Soto and Guerra were killed just before midnight Dec. 21, officials said, but they were not reported missing until Dec. 23. She was scheduled to be induced shortly before her disappearance.

She had planned to name the unborn child Fabian, Soto’s family said.

This article was originally published on NBCNews.com