Coroner's investigators determined the body discovered Tuesday was that of 22-year-old Brittany Dawn Killgore.
The disclosure came a day after authorities arrested Jessica Lynn Lopez, 25, on suspicion of murder and continued to investigate Louis Ray Perez, the last person seen with Killgore, as a person of interest in the case.
Authorities have not disclosed how the three know one another.
Perez, 45, pleaded not guilty Wednesday to stealing an assault weapon. Investigators have given few details about that case, and it was not known if they suspect the weapon was tied to Killgore's death.
Perez was being held on $500,000 bond. His attorney Jeffrey Reichert said his client has no criminal history, is married and has lived in San Diego County for 10 years.
Lopez was scheduled to be arraigned Thursday.
Killgore went missing shortly after filing for divorce from her husband, a 22-year-old Marine deployed to Afghanistan. Her body was found in brush near Lake Skinner in Riverside County about 25 miles northeast of her modest, two-story apartment in Fallbrook, a San Diego County community known for its avocado orchards.
Killgore lived a short walk from an entrance to Camp Pendleton, and her complex - like others around it - is full of Marines and their families who tend to be short-term residents and often don't get to know each other well.
Killgore's husband, Lance Cpl. Cory Killgore, was flying back to California after learning his wife was missing. Sheriff's authorities say he is not a suspect.
The couple from Missouri were married in July 2010. Brittany Killgore filed for divorce April 10 and listed "irreconcilable differences" as the reason. She gave no details on the paperwork.
Her cellphone was found in the Gaslamp District of downtown San Diego.
Darryl J. Wrest of Rolla, Mo., confirmed Brittany Killgore is his daughter but said he was not commenting on anything at this time. Killgore's other family members also declined to comment.
Associated Press