Nuhu Ribadu was accused of only investigating the president's rivals
Nigeria's powerful anti-graft agency has appointed a new head, five months after moving the former chairman out on "study leave".
Farida Waziri, a retired Assistant Inspector General of Police will take over at the Economic and Financial Crimes Commission (EFCC).
The EFCC was set up to tackle Nigeria's huge problem of corruption.
But critics say it has instead become a tool for settling political scores and the most corrupt remain untouched.
The BBC's Alex Last in Lagos says the fight against corruption has become the main weapon used against Nigeria's political elite, so the choice of who heads the main anti-corruption agency is important.
He says that these days former President Olusegun Obasanjo, who set up the EFCC, and senior members of his administration are the popular target of choice.
Nuhu Ribadu was removed as EFCC chairman last December after he began investigating a former state governor - one of eight currently facing trial on corruption charges.
He had been accused of only investigating the political rivals of former President Obasanjo - charges he denied.
The new chairwoman is a former head of the police anti-fraud unit.
She trained Mr Ribadu before he moved to the EFCC, local press reported.
Our correspondent says she is well respected among law enforcement agencies, and is said to have a tough, no-nonsense approach.
She is the author of a book on "advance fee" fraud, is married to the former Nigerian ambassador to Turkey, and has four children, the Punch newspaper said.
Breaking the cycle
But our correspondent says the question is: Does she have the will and the political backing to really go after people?
He says that in Nigeria, where oil money flows, politics, patronage and corruption are inextricably linked.
Breaking the cycle means breaking a whole political system, and few in power have the will, let alone the strength to do that, he says.
Nigeria is often ranked as among the world's most corrupt countries by watchdog Transparency International.
The government estimates Nigeria has lost around $400bn to graft over the decades.