Third person arrested in connection with the killings of pregnant teen and her boyfriend, police say

(CNN) — A woman has been arrested in connection with the killings of a pregnant Texas teen and her boyfriend after their bodies were found last month in a car in San Antonio, authorities said – the third arrest in the case.

Myrta Romanos, 47, was arrested on charges of abusing a corpse, altering, destroying or concealing a corpse and tampering with evidence, San Antonio police said at a Wednesday news conference.

Police said they believe she is the stepmother of a 19-year-old suspect arrested earlier this month.

The bodies of 18-year-old Savanah Soto, who was nine months pregnant, and 22-year-old Matthew Guerra were found, each with a gunshot wound, in a car parked near a San Antonio apartment complex on December 26, police had said.

Soto, who was past her delivery date, was reported missing by her family when she missed an essential medical appointment, according to police in Leon Valley, Texas.

On January 4, Christopher Preciado was arrested on suspicion of capital murder in their deaths, the San Antonio Police Department said in a news release on Facebook. The 19-year-old’s father, Ramon Preciado, 53, was arrested on charges of abuse of a corpse, the release said, accused of helping his son “move the bodies.”

CNN is working to determine whether Christopher Preciado and Ramon Preciado have legal representation.