Ex-chief of defence staff Alex Badeh was shot dead in his car by unknown gunmen on a road outside the capital Abuja last December.

The retired air chief marshal and his company were being prosecuted by the Economic and Financial Crimes Commission (EFCC) over allegations of abuse of office and money laundering.

He allegedly diverted nearly $20 million (17.6 million euros) of government funds, including money meant for salaries, for his own use.

Some of the cash was allegedly used to purchase a mansion in the upmarket Maitama district of the city,

Badeh, 61, served as Nigeria's defence chief under former president Goodluck Jonathan, as Boko Haram Islamists seized territory across the northeast.

At the time, Nigerian troops complained the jihadists were better armed, and that they were not being paid or provided with food.

In a ruling on Monday, federal high court judge Okon Abang ordered the forfeiture of various luxury properties in Abuja and $1 million recovered from his company to the government.

The properties include the house in Maitama, a shopping mall and three apartments, the EFCC said in a statement.

Police said in December that five suspects were arrested in connection with his death.

Nigeria is battling a myriad of security problems, from Boko Haram in the northeast to farmer-herder conflict in the centre, kidnappings and armed robberies in the south.

Funds meant to be used to procure weapons to battle Boko Haram were allegedly looted by top defence and security chiefs under president Jonathan.

His successor, Muhammadu Buhari, who came to office in 2015 and last week won a second term, has vowed to recover all looted funds.