Provincial court Judge Tracey Lord has granted permission to the lawyers for accused letter bomber Guido Amsel to cross examine a detective who prepared the information to obtain a DNA warrant in the investigation.

In her decision, Lord told court Tuesday morning the cross examination can only deal with questions about an August 25, 2015 report on test results from a swab of Amsel's hands.

A preliminary test found traces of an explosive substance but needed to verified with a second report, court heard on Monday.

Amsel's lawyers have taken issue with the exclusion of the results of the second test from the information to obtain, which came back negative.

READ MORE: Amsel defence challenging DNA warrant

Cross examination is scheduled for Wednesday morning.

Lord ruled not to allow cross examination of investigating officers who contributed to the information to obtain and ruled against allowing the defence to ask questions about a handwriting analysis report.