Interfax-Ukraine reported Prosecutor General Viktor Pshonka said at a news conference Friday his office had notified Tymoshenko and former Prime Minister Pavlo Lazarenko they are suspected of organizing the killing of Yevhen Scherban. Pshonka suggested there were business reasons behind the killing.
They could be sentence to life in prison if convicted.
Scherban, a member of the Liberal Party's executive committee and a Verkhovna Rada deputy, was shot to death when he arrived at the Donetsk airport from Moscow on Nov. 3, 1996. His wife, his mechanic and the plane's flight engineer also died in the attack. Vadym Bolotskykh is serving a life prison term for carrying to the shooting.
Scherban's son, Ruslan Scherban, said last April he had provided prosecutors with documents indicating Tymoshenko and Lazarenko might have played a role in killing his father. Tymoshenko and Lazarenko denied any involvement.
Tymoshenko's attorney said late last week the former prime minister was critically ill in a hospital in Kharkiv.
Tymoshenko is serving a seven-year prison term for abuse of office after negotiating a gas deal between Russian and Ukraine in January 2009.
She maintains her conviction was politically motivated by President Viktor Yanukovych.
Tymoshenko was moved to a hospital last year after complaining of deteriorating health in prison.