Three people have been arrested in Lagos, southern Nigeria, for allegedly hacking at least 5,000 people in more than 150 countries.
They were arrested following a joint operation by Interpol and the Nigerian Police Force to combat cybercrime.
The one-year study, dubbed Falcon, identified at least 50,000 people affected.
He has been accused of using the Internet and sending large numbers of messages to members of the military.
Experts say cyber-attacks have increased in Nigeria during the cholera epidemic.