A 92-year-old woman died on Wednesday afternoon after being stabbed at her home in Sanlúcar de Barrameda, Cádiz province, allegedly at the hads of her son.
The detainee, 64-year-old C.O.M., also injured himself with the same weapon and is now in hospital in Jerez.
Police arrived at the home in calle Diosa Atenea at around 14:45 shortly after another son of the victim, who had received a phone call, arrived at the home to find his mother injured.
When medics arrived on the scene the woman had already died. They treated the suspected attacker and transferred him to hospital.