The Jakarta prosecutor's office is eying new suspects in a case involving the alleged mark-up in printing costs for vehicle tax forms following the arrest of former city revenue agency head Deden Supriyadi.

"We're still investigating the case. We will see how it progresses in the next few days," office spokesperson Mustaming told The Jakarta Post Tuesday.

The office chief, Harry Hermansyah, said more suspects would soon be revealed, saying corruption cases usually involved many people.

He also said the office would submit the dossiers on Deden's case next week to the Central Jakarta District Court, Harry told reporters at City Hall after a meeting with Deputy Governor Prijanto.

According to Mustaming, the office arrested Deden last Friday for allegedly misusing Rp 2.6 billion (US$2.8 million) in taxpayers' money on the printing of vehicle tax forms when he headed the agency.

Deden was in office from 1999 to 2004 before being promoted to assistant to city secretary for economic affairs. He has since retired.

The arrest was made two days after Deden's former position was officially replaced by Sukri Bey.

According to Mustaming, Deden did not carry out public bidding for the agency's printing and so agreed to directly appoint a printing company to produce the tax forms, breaching a presidential decree on goods and services procurement.

He also said the budget provided for printing tax papers was higher than that in 2005, when the agency held public bidding to single out a printing company.

"We know printing costs rise annually. But why was the cost so much higher during the 1999-2004 period compared to 2005?" asked Mustaming.

Jakarta's Legal Aid Institute director Asfinawati said she suspected there were other parties involved in the case.

"It is impossible for one person to have misused the funds alone," she said.

"I strongly suggest the office probe this case thoroughly. Otherwise, Deden's arrest will have been a mere formality," she said.

She said the office should also grill, for example, Deden's seniors or colleagues in the appointed company.

According to Mustaming, the office has also named six suspects for having misused Rp 15 trillion in taxpayers' money in 2006 to acquire a multipurpose filing cabinet.

Harry said the office arrested eight suspects, all from Jakarta.

The suspects are bidding chief Rusmadi and the director of CV Karya Pratama from West Jakarta, and bidding chief Tri Witjaksono and CV Darmakusumah director Wawan Subhan from South Jakarta. Two more suspects, identified by their initials only, are HAD from Central Jakarta and RT from North Jakarta.

"We are yet to finish investigating the case in East Jakarta," he said.

He also said the office might question other city officials and city councillors allegedly involved in the case.