Police have made an unexpected new arrest in connection with the long-running investigation into a phishing gang that stole £1.5 million ($2.5 million) from the banks accounts of UK-based students in 2011.

On 18 December, police picked up an unnamed 34 year-old Nigerian man in Manchester, removing a haul of computers and phones as part of the investigation.

Earlier this week, what appeared to be the final significant member of the Nigerian gang, Olajide Onikoyi, was sentenced to three years and nine months in prison, the fourth person convicted for the attacks. It now looks as if the investigation is ongoing.

A total of 12 people have now been arrested in connection with the August 2011 attacks, with the first being found guilty as long ago as July 2012. Further convictions followed in February 2013, followed by another two this month, including that of Onikoyi.

"We've made this arrest in connection with an ongoing investigation into offences which date back to 2011. This shows our utter commitment to pursuing those suspected of cyber crime. In this case, the victims are students and banks,” commented detective inspector Sanjiv Gohil of the MPS Cyber Crime Unit.

"We work really closely with the banking industry to locate and bring to justice those who seek to profit from illicit cyber activities, especially at the expense of innocent members of the public."

During the 2011 attacks, the gang used a phishing email to trick an estimated 1,300 students into revealing their financial details on a bogus website set up to look like that of the Student Loans Company.

Police said they believed the latest individual 0arrested had been involved in “controlling a botnet,” presumably the one used to send the emails that set up the attacks.

Because it often crosses multiple international borders, phishing is a crime that can be notoriously difficult to prosecute. However, the MPS Police Central e-Crime Unit and its new successor the National Cyber Crime Unit have gone to unusual lengths to track down phishing attack gangs with a domestic origin.