A Nigerian court the criminal case between Pfizer and Nigeria’s northern Kano state, which is seeking $2 billion over allegations that a decade-old study led to deaths and disabilities in children.

Presiding judge Shehu Atiku said the delay would allow the prosecution to serve a summons requiring Pfizer executives to appear in court when the trial resumes on Oct. 3. They did not appear Monday because they had not been officially summoned. Defendants in the federal criminal actions include former Pfizer ceo Bill Steere and six other people who worked for Pfizer in 1996.

Kano state has also launched a separate civil case, which will be heard in Kano on July 30. That case doesn’t require Pfizer execs to be present as long as they are represented by their lawyers. The Nigerian federal government has also filed a third suit in the capital of Abuja, seeking damages of US$7 billion.

Pfizer has denied the charges. The mid-1990s study used a group of 200 children to test an experimental meningitis treatment. The study took place during a 1996 meningitis epidemic in Kano state’s main city, also called Kano.