The trial against those accused over the sinking of the Prestige is expected to deliver its verdict later on Wednesday.
The Prestige oil spill in November 2002 was Spain’s worst ever environmental disaster.
The prosecution has asked for a 12 year jail term for the 78-year-old captain, Apostolos Mangouras, his Greek chief engineer Nikolas Argyropoulos and the then head of the Spanish merchant navy, Jose Luis Lopez Sors.
The prosecution has also demanded more than four billion euros in damages.
The captain is charged with harming the environment as well as other charges related to damage of a protected environment.
The Prestige oil tanker was heading from Lithuania to Gibraltar when it had an accident and started taking in water during a storm.
It sank six days later dumping 77,000 tonnes of fuel into the sea causing serious damage to wildlife and livelihoods. Several hundred kilometres of coastline were coated in oil sludge.
The captain blamed the spill on the Spanish authorities who ordered the ship out to see after it sent out a distress call because of a crack in its hull.