(CNN) -- Ethiopian ex-dictator Mengistu Haile Mariam may be forced from exile in Zimbabwe to face a death sentence at home if President Robert Mugabe is ousted in an upcoming election, an opposition spokesman indicated Tuesday.
Mengistu Haile Mariam in 1986. He is now living in exile in Zimbabwe.
Mengistu, who fled to Zimbabwe after he was deposed in 1991, was sentenced to death on Monday after he was found guilty in absentia of committing genocide during his 16-year rule.
With no extradition treaty, according to legal experts, Mugabe's government is unlikely to act on the ruling, but the situation could change if his Movement for Democratic Change (MDC) rivals win a June 27 presidential vote runoff.
"The MDC would believe that justice for Ethiopians is justice for Africa," MDC spokesman Nelson Chamisa told CNN.
"Mengistu should be able to ... answer for his personal missions and commissions. We have international statutes, international obligations to the
Chamisa stopped short of saying the MDC would extradite Mengistu, but added: "I've tried as much as possible to indicate the direction we're likely to take.
"It is important that others lean in that direction, considering the fact that the people in Ethiopia, in order for them to have national healing ... they would want to execute.
"So as a government, we are not going to be an impediment to the realization of the truth," Chamisa said. He added that his party does not, however, support the death penalty.
Wednesday is a national holiday in Ethiopia, the day when the country celebrates the end of Mengistu's regime, known as the Derg.
The Ethiopian Information Ministry published a brochure for this year's holiday reminding Ethiopians about "the oppression and tyranny" the country suffered under Mengistu, according to the national Ethiopian News Agency.
Mengistu rose to the top of a ruthless military dictatorship after a 1974 military coup ended Emperor Haile Selassie's 44-year rule.
Backed by financing from the Soviet Union, Warsaw Pact countries and Cuba, he oversaw the "red terror" purges of 1977 and 1978 in which thousands of suspected Derg enemies were tortured or killed, the U.S. State Department says.
Droughts, famine and insurrections eventually led to the Derg's collapse, prompting Mengistu to flee to Zimbabwe.
Mark Ellis, executive director of the International Bar Association in London, England said any future extradition of Mengistu could present problems for Zimbabwe.
"Zimbabwe, under international law, does have a duty not to provide safe haven for individuals that are accused of committing these crimes, and they certainly can't give impunity to them," he said.
"In a post-Mugabe resume, then a new government could extradite him back to Ethiopia, but I still think there'll be an issue involving the death penalty."
A possible solution is for Zimbabwe to request a new trial, with Mengistu facing the charges in person and without the possibility of execution, Ellis said.