After former President Goodluck Jonathan left office, the accusations of corruption, fraud and embezzlement became especially stronger.
With President Buhari's insistence on fighting corruption and the many arrests being made, many officials who served under Jonathan and who had corruption cases hovering over them, decided it was best to leave the country.
Here are some who are currently on self-imposed exile from Nigeria:
1. Bello Fadile
Retired colonel Bello Fadile was one of those who came out against Olusegun Obasanjo, threatening to jail him in 2014.
During Jonathan's rule, Fadile was a close friend of Sambo dasuki, the former National Security Adviser.
Fadile was also a director of special duties in the Office of the National Security Adviser (ONSA), under Dasuki.
Fadile is currently being investigated for his alleged role in the $2.1 billion arms scandal which got Dasuki arrested.
In July 2015, Dasuki and Fadile were placed under house arrest by the State Security Service, (DSS), in July 2015 after which Dasuki was arrested and still remains in the custody of the SSS despite several court orders.
Meanwhile, Mr Fadile left the country and he is said to currently be in the U.S.
2. Government Ekpemupolo
In October 2009, he embraced the amnesty program to allow the government and the oil companies carry out development projects in the region.
He wielded a lot of power under Jonathan's administration and the EFCC have declared him wanted in a case of conspiracy and illegal diversion of the sum of N34, 000,000,000 (Thirty Four Billion Naira) belonging to the Nigerian Maritime Administration and Safety Agency, NIMASA.
Tompolo is currently on the run and from his hideout, he has denied involvement in the N34 billion fraud.
“The truth of the matter is that I do not know anything about the 34 billion naira EFCC is talking about. First, it was 13-billion naira (N13bn) issue, now it is 34 billion naira (N34bn).
"I am not a signatory to any of the companies mentioned in the said N34bn case, so I do not know where this one is coming from," he said in one of the many open letters he has written to Buhari.
3. Diezani Alison-Madueke
Diezani Alison-Madueke was the petroleum minister under Jonathan's rule. The former director at Shell’s tenure as petroleum minister turned out one of Nigeria’s most controversial, as corruption allegations continued to come up.
Under her watch, probes by independent audit firms, including the KPMG, confirmed billions of Naira of oil money was mismanaged.
In 2014, the then governor of Central Bank of Nigeria (CBN), Lamido Sanusi, alleged in 2014 that the missing money was about $20 billion.
She is also involved in various scandals surrounding the sale or lease of Nigeria’s oil blocks. In October last year, she was arrested in London along with others by the UK National Crime Agency.
Nigeria’s EFCC operatives raided her Abuja home, located in the Asokoro district of the federal capital city, and sealed the property, after they reportedly recovered expensive jewelries and other items from the building.
Mrs Alison-Madueke is believed to be in the United Kingdom where in 2015 she received treatment for cancer.
4. Kingsley Kuku
Under Jonathan's rule, Kingsley Kuku was his special adviser on Niger Delta Affairs. He was also the chairman of the presidential amnesty programme.
In July 2015, the EFCC summoned Mr Kuku for questioning over his part in the alleged embezzlement and fraudulent diversion of funds running into hundreds of millions of Naira in the Amnesty Office.
Mr Kuku was asked to appear before the EFCC on July 28, 2015 but requested to be allowed to honour the invitation on September 30, 2015. He however left the country and is suspected to be in the US.
He has insisted that he only travelled to on medical grounds.
5. Mohammed Bello Adoke
Mohammed Adoke was Nigeria’s Attorney-General of the Federation and Minister of Justice under Jonathan's rule.
The Senior Advocate of Nigeria (SAN), was appointed into the office on April 6, 2010, and he had supervisory control over prominent law enforcement agencies including the EFCC.
He has been accused of taking part in at least three major multi-billion dollar deals. They include the $1.1 billion Malabu oil payment deal; $2.1 billion arms fund diversion and recently, the alleged diversion of $1.6 billion local government judgment fund.
The EFCC filed charges against Mr Adoke and others, at the Federal High Court, Abuja, in respect of the Malabu oil deal.
Mr Adoke has since left Nigeria for Netherlands, presumably to pursue a law programme at the prestigious Leiden University.