SA police probe NCA bombing witnesses

Police want to hear back from a person who provided "critical" information about the 1994 bombing of the National Crime Authority offices in Adelaide.

The person, who provided the information to CrimeStoppers at about 8pm (CST) on Saturday, April 2, has been urged to call back to speak to an investigator.

Detective Sergeant Geoffrey Bowen died when he opened a parcel bomb delivered to the NCA office in Waymouth Street in the CBD.

A lawyer, Peter Wallis, was seriously injured.

Adelaide man Domenic Perre was arrested over Det Sgt Bowen's murder but charges were dropped six months later because of a lack of evidence.

Police have received 16 calls since establishing a new taskforce in April to renew investigations into the bombing.

Major crimes detective Des Bray said the taskforce was zeroing in on witnesses who had fabricated or withheld information in the past.

"The renewed investigation has uncovered significant information not previously known to police and, as result, we now have a much clearer understanding of what occurred," he said on Tuesday.

"There are some people who may have fabricated or withheld information from police in the past, and these people are a focus of the investigation."

A $1 million reward for information that leads to a conviction remains in place, he said.