Mexico’s President Enrique Pena Nieto says police arrested a man who killed his wife and then himself in their Mexico City home on Saturday.
He did not provide details of the incident.
A Mexican federal police spokeswoman said a man was found dead inside the house in the western town of Sinaloa.
She said the death was an accident.
The woman’s death was not immediately confirmed.
The Mexican state prosecutor’s office said it had opened an investigation.
In September, Mexico’s Interior Ministry said it was investigating the death of a woman who was found in her home by a member of the national guard.
The Interior Ministry later said the woman had died of natural causes.
The ministry said the man, identified by a spokesman as Mario Rodriguez, was arrested.
He is a member, not a deputy, of the National Guard, the spokesman said.
He was also in the police’s custody as of Sunday.
The interior ministry added it was in contact with other Mexican authorities.
It said that in the wake of the investigation, the national police and other security forces were “committed to conducting a thorough investigation into the events that occurred.”
Reporting by Eliza Lambert and Alex Dobuzinskis in New York, Daniela M. Solis in Madrid and Ana Paula Sanchez in Mexico City contributed to this report.