Tymoshenko is alleged to have played a role in the 1996 contract killing of Ukrainian lawmaker Yevhen Shcherban and his wife. Authorities claimed Tymoshenko and former Prime Minister Pavlo Lazarenko paid for the killing.
The Prosecutor General's Office said was reopening the murder case against Tymoshenko, Russian news agency RIA Novosti reports.
Tymoshenko was sentenced in 2011 to seven years in prison after being convicted of charges she abused authority in a gas deal with Russia's Gazprom. Her lawyer Sergei Vlasenko said the case was closed in April, though prosecutors said it was only suspended.
Tymoshenko's political allies say the charges against her are politically motivated. The European Court of Human Rights ruled last month that some of her rights had been violated.
U.S. Secretary of State John Kerry raised the issue last week alongside Ukrainian Foreign Minister Leonid Kozhara. Kerry said he hoped the Ukrainian government would work on "the ending of the prosecution of some people, and particularly former Prime Minister Tymoshenko."