The registered owner of a tanker controlled by Evangelos Marinakis' group of companies and three of its engineers have pleaded guilty to felony pollution charges in Los Angeles.

But prosecutors have promised not to go after the ship's beneficial owner and manager, Marinakis-backed New York-listed Capital Product Partners and his private Capital Ship Management.

Amoureux Carriers Corp, owner of Capital Product's 149,900-dwt tanker Amoureux (built 2008), agreed to plead guilty to a single charge of failing to maintain an accurate oil record book. In the plea agreement, prosecutors have specifically agreed not to prosecute Piraeus-based Capital Ship Management.

A source with knowledge of the case said that Capital Product, in which Marinakis is the largest shareholder, will also not be prosecuted as a result of the single-ship owner pleading guilty to vicarious liability. The Amoureux trades in the Stena Sonangol Suezmax Pool.

Amoureux Carriers agreed to submit to a three-year probation sentence, a stringent regulatory compliance programme, and a $700,000 fine to be paid over three years.

Romanian chief engineer Gheorghe Amza’s guilty plea has resulted in a three-year probation and a $200 assessment, and the plea agreements for engineers Marius-Stefan Marinas and Sandu Gheorghita are understood to be on similar terms.

A source said the ship's manager and beneficial owner were not drawn into the prosecution because it was clear they were unaware of the alleged conduct and because the engineers acknowledged they had hid it from the vessel's master.

It is unclear whether the company will be around to see the end of its probation term. In December, the Amoureux was reportedly sold to Shipping Corp of India for about $32.5m. However, no such sale has been confirmed, and the ship remains listed in Capital Product's owned fleet.

Meanwhile, although pleas in the case were filed in early January, it is still ongoing as prosecutors and defence lawyers submit pleadings and evidence under seal on the question of awards to whistle-blowers who gave information during a call at Los Angeles last May.

A clause in the shipowner's plea deal with local prosecutors reserves its right to file a memorandum on the amount of money to be paid to whistle-blowers.

A series of documents on the whistle-blower question have been filed in the case but are unavailable in the public court record.

Up to half of the criminal fine in such cases can be paid out as rewards to whistle-blowers.

Such rewards do not increase the fines paid by the shipowner, but shipowners have historically contested them for fear of incentivising their low-wage crew members to create pollution violations for the sake of awards equal to many times their annual earnings.

Amoureux Carriers is enrolled in the West of England P&I Club. The shipowner was represented by George Chalos of New York maritime law firm Chalos & Co.

Chalos declined to comment on the case.