There was growing alarm this week at the high death rate in old people's homes in different parts of the country, but especially in Madrid.
In some cases, stories were emerging of the bodies of dead residents being left in their beds without telling relatives. Staff were going sick or leaving to avoid catching coronavirus.
Army emergency medical teams visited 41 care homes across the country before prosecutors on Monday received a formal request from the Ministry of Defence for an investigation into why the death rate was so high. The level of care inside some of the private and public homes visited was being openly questioned, but army officials stressed that the incidents were not generalised across all centres.
The government said this week that a care home should tell the regional health authorities immediately if they could not cope with a situation.
On Wednesday official statistics said that 50 people had died in care homes for the elderly in the last 24 hours. One home in Madrid, Santísima Virgen y San Celedonio, said it had so far had 24 residents die with coronavirus as well as a nun from the charity that ran it.
Meanwhile, one small private residence outside Madrid (that so far has nobody infected with coronavirus) pleaded with health officials not to send residents for the two spare spaces it has without testing the newcomers first.