Alexei Pichugin, the former security chief of Yukos, Russia's embattled oil company, was on Wednesday jailed for 20 years for murder the first company official to be sentenced in the controversial affair.
The prosecutors had demanded a maximum sentence of life-time imprisonment for Mr Pichugin, who last week was found guilty by a jury of murdering a married couple and attempting to murder a Moscow city hall official. The bodies of the married couple were never found.
Prosecutors on Wednesday said he could face new charges in related investigations.
The sentencing comes only a day after prosecutors also demanded a maximum 10-year prison term for Mikhail Khodorkovsky, the former chief executive of Yukos and its key shareholder, and for his close associate, Platon Lebedev. Both are accused of fraud and tax evasion.
Tax collectors on Wednesday asked the court to enforce a $700m (€540m, £370m) claim against Mr Khodorkovsky and Mr Lebedev. The trial of Mr Khodorkovsky and his business associates was accompanied by a huge assault on Yukos by the state, including a crippling $27.5bn tax claim.
The main production unit of Yukos has been sold in a forced auction and ended up in the hands of Rosneft, a state-owned oil company chaired by the deputy head of the Kremlin administration.
Mr Pichugin's lawyers say his only guilt was working for Yukos and refusing to implicate his former bosses. The prosecution said Mr Pichugin received his orders from Leonid Nevzlin, a close associate of Mr Khodorkovsky. Mr Nevzlin who is wanted by Russian police on charges of murder and attempted murder has fled to Israel. Mr Nevzlin denies any wrongdoing and claims the whole case is fabricated.
The prosecutor on Wednesday also said that Mr Khodorkovsky's name was mentioned several times by witnesses during Mr Pichugin's investigations.
Mr Pichugin's trial was held behind closed doors and his lawyers alleged that he had been injected with drugs during the preliminary investigation. His lawyers said they would appeal against the sentence and are planning to complain to the European Court of Human Rights in Strasbourg.