SAN DIEGO (AP) — A man captured in Mexico last month has pleaded not guilty to killing his stepmother and half-brother in San Diego County to keep them from talking about his alleged sex assault on another family member.

Prosecutors say Marco Antonio Valadez entered pleas Monday in San Diego to two counts of murder with special circumstances. He'd be eligible for the death penalty if convicted. He's also accused of sexually abusing an 18-year-old family member.

Prosecutors allege that Valadez shot his relatives on Dec. 4 in Imperial Beach while trying to keep them from being potential witnesses following disclosure of the sex crimes.