The Judicial Police is investigating the possibility of explosive detonations at the Borba quarry, just hours before the accident on November 19th, when a public road collapsed, killing five people.
The investigators have interviewed several witnesses who say they heard at least two detonations before a section of the EN225 gave way.
Explosive charges are permitted in quarries as long as stringent safety rules are observed.
The Ministry of the Environment commented that the Directorate-General for Energy and Geology had authorised the use of 75 kilogrammes of gunpowder in the Borba quarry, in an order issued on March 1, 2017.
The investigators also are reviewing other factors that may have contributed to the road collapse, including heavy rains the previous weekend and an earthquake in the area that reached magnitude 2, as recorded by the Institute of the Sea and Atmosphere, a day before the accident.
This Saturday another car was removed from the water-filled quarry. The fifth victim, an 85-year-old man, was still inside the vehicle.
The car was located on Friday, the day the bodies of two of the three remaining people were recovered from the water.
