Investigators in Texas were trying to understand late Thursday what led to an apparent murder-suicide inside a Helotes church earlier that day.

Officers believe Manuel Rodriguez, 51, shot and killed 54-year-old Zeferina Castillo before turning the gun on himself, the San Antonio Express reported.

The bodies of the pair were found Wednesday afternoon near the altar of Our Lady of Guadalupe Catholic Church in Helotes, the Houston Chronicle reported. Neither of the pair, who both lived in nearby San Antonio, was a parishioner at the church.

Police spokesman Anthony Burgess said, "All we know is they were involved -- apparently for a while. And what 'a while' is, I can't really define that."

Investigators have determined that Rodriquez shot Castillo several times in the upper torso before firing a single bullet into his own head. They do not know what the man's motivation was.

Rodriguez and Castillo were reported to have arrived at the church in separate vehicles and walked in calmly. "There was no push, no grab, no tussle. It looked like they were just walking into church," Burgess said.

Motion-sensitive CCTV cameras in the church recorded the man and woman walking toward the altar but stopped recording when the pair stood still, police lieutenant Elliott Rodriguez told the Chronicle.

Shots were heard at about 3:00pm local time, and a police officer later found two bodies close together on the floor between a baptismal font and two steps that led to the altar, with a pistol between them.

They were the only ones in the church at the time of the shooting, Rodriguez said.