Updated

Mexican authorities say they have arrested one suspect in the kidnapping of a Spanish woman whose body was found last month in neighboring Mexico state.

Deputy Attorney General Gustavo Romulo Salas said in a news conference Monday that a suspect arrested Sunday was involved in Maria Villar Galaz's abduction, but not her killing.

Villar got into what she believed was taxi in an upscale Mexico City neighborhood on Sept. 13. Salas says that shortly after she entered the taxi, it stopped and the man arrested Sunday got in. He says she was immobilized by a stun gun.

The motive was to withdraw money from ATMs using her bank cards.

Salas says demanding a ransom and later killing Villar were decisions taken on the fly. Her body was found Sept. 15.