Former Prime Minister Yulia Tymoshenko, now imprisoned for other offenses, had been accused of organizing the murder of Parliament member Yevhen Scherban in 1996.
Her defense attorney, Serhiy Vlasenko, said the prosecutor's action was "further confirmation of what the defense team has always said – the Scherban case is non-existent." Interfax-Ukraine reported Monday.
Scherban, his wife, a mechanic, and a flight engineer were shot and killed by gunmen at the Donetsk airport after his arrival from Moscow on Nov. 3, 1995.
Vadym Bolotskykh was arrested for the murders and sentenced to life imprisonment in April 2003. Scherban's son reported in April 2012 that he had given documents to the Prosecutor General's Office indicating Tymoshenko and former Prime Minister Pavlo Lazarenko might have been involved in the murders.
Tymoshenko and Lazarenko have denied any involvement in Scherban's death.
Tymoshenko is serving a seven-year prison sentence for her 2011 conviction for overstepping her authority in signing gas contracts with Russia in 2009.
The United States maintains she should be released from prison.
U.S. Ambassador John Tefft said Monday "our position remains unchanged" that Tymoshenko should be released soon.
Tefft said her potential release was discussed in a recent meeting between U.S. Secretary of State John Kerry and Ukrainian Foreign Minister Leonid Kozhara.