Jonathan Goodluck has been sworn in as the new governor for Nigeria's oil-rich Bayelsa state after the previous governor was impeached last week.
Mr Alamieyeseigha says his prosecution is political
Diepreye Alamieyeseigha was arrested after his impeachment and could be sent back to the UK to face charges of money-laundering up to £1.8m ($3.2m).
Mr Goodluck was the deputy governor and is to stay in office until 2007 polls.
He promised to reduce poverty in what is one of Nigeria's most deprived areas, despite its oil wealth.
ThisDay newspaper reports that security was tight for the swearing-in ceremony.
"I enjoined my fellow Bayelsans, and indeed all people of the south, not to be dampened by the sad events of the recent past," Mr Goodluck said in his inaugural speech.
"On the contrary, I urge old and young to use this incident to reposition the state for a better future. "
Mr Alamieyeseigha skipped bail in the UK to return home to Bayelsa, hoping to benefit from the immunity from prosecution enjoyed by governors.
But he was widely condemned. President Olusegun Obasanjo said he had brought "shame" on Nigeria.
Last year, another Nigerian state governor returned home after being arrested in London . Joshua Dariye from Plateau state was quizzed by police on money laundering allegations involving more than £1m ($1.75m).
Mr Alamieyeseigha denied the charge of money laundering and said the money allegedly found in his house and bank accounts did not belong to him.
He said the charges against him were politically motivated.
As Nigeria battles to shed a reputation for corruption, this is the first time under President Obasanjo that a governor has been impeached.
On the run
Mr Alamieyeseigha is also facing allegations of fraud by a special anti-corruption court sitting in the northern city of Kaduna.
"The cover of immunity has been taken away from him by the impeachment. We are going to move in immediately... The man has several cases against him. Everyone wants him," Osita Nwajah, spokesman for Nigeria's Economic and Financial Crimes Commission (EFCC) told AFP.
The president set up the EFCC anti-corruption body in order to fight fraud in a country ranked as one of the most corrupt in the world.
But his critics say the anti-corruption drive is bring used to eliminate political rivals.
Mr Alamieyeseigha is seen as being close to Vice-President Atiku Abubakar - who is vying with Mr Obasanjo for control of the ruling People's Democratic Party (PDP).
Earlier this month, the governor was suspended from the PDP.