The Kerala [Images] police on Sunday claimed to have cracked the case related to e-mail threats against the President and the prime minister with the arrest of a man named Akbar Raj, who allegedly sent the messages from a cyber caf� in Kochi.

The investigation showed the motive behind the crime was to cause trouble for a girl whom Raj had known through chatting on the Internet, Director General of Police Raman Srivastava and DIG Padmakumar said.

However, further inquiries will be made to ascertain whether Raj had any links with any organisation, they said.

The man had sent the threatening e-mails that had a link pointing to the girl, a resident of Kottayam.

Raj, 26, a computer instructor and hardware expert, sent malicious e-mails to the girl.

The police were able to trace the girl's address by decoding the link in the e-mails, which Raj had sent to senior police officials on October 26.

The resident of Cherthala in Alappuzha district was picked up late on Saturday night.

Investigations revealed that the girl had earlier complained that Raj had sought to create trouble for her.

According to the police, Raj has confessed to having sent the e-mails and the staff of the Internet caf� from where the messages were sent had identified him.

The e-mails prompted police to take a serious note of the matter as Prime Minister Manmohan Singh [Images] is scheduled to visit Kerala on November one for events to mark the state's formation day.