Chevron Corp.’s lawyers have picked off another target in their campaign against those involved in a lawsuit accusing the oil giant of damaging the Amazon rainforest in Ecuador. On Monday, a key financial supporter of the environmental litigation, Gibraltar-based billionaire James Russell DeLeon, renounced his association with the case.

Chevron settled tort claims against DeLeon in Gibraltar over his funding of an Ecuadorean lawsuit that, in 2011, led to a $19 billion environmental judgment against the oil company, which was later cut to $9.5 billion on appeal.