Debra Ayala Tapia is charged with two felony counts of lewd acts upon a child, two felony counts of oral copulation of a minor under 16, and two felony counts of unlawful sexual intercourse, according to the Orange County District Attorney's Office.
"She found it odd and started investigating," says Santa Ana police Cpl. Anthony Bertagna.
"She talked to her son about the letters and he admitted that he had sexual intercourse with the woman."
The boy's mother noticed that the woman, who was a neighbor and family friend, was pregnant, Bertagna said.
The woman gave birth to a baby girl in November 2009 and a DNA paternity test performed in February showed the boy was the father, he said.
The boy's mother reported the incident to Santa Ana police on March 14, Bertagna said.
Detectives interviewed the boy and Tapia and learned that they had a consensual sexual relationship from March to September 2009, Bertagna said.
Tapia was married at the time of the unlawful sexual relationship and has three children ages 17, 12, and 7.
She is free on $100,000 bail.