A defence lawyer for Robert William Pickton challenged the credibility of a key Crown witness whose information prompted a police search on Pickton's property.

Scott Chubb told police about weapons on the Pickton farm in early 2002, which led to a firearms search of the property. Police quickly discovered belongings of some missing women and a new search warrant was obtained.

Chubb told the trial Tuesday he came forward to police because he was being a "concerned citizen," a comment that brought laughter from the public gallery and smiles from some members of the jury.

The defence alleges Chubb came forward because he needed money.

During a heated and aggressive cross-examination, defence lawyer Peter Ritchie took aim at Chubb's credibility and his memory of events.   

He denied being a paid police informant, saying he received no money from the police. But when Ritchie showed him the police officer's notes that said Chubb received $750, Chubb reluctantly admitted his signature was there.  

Ritchie pressed Chubb on his financial situation and drug habits, suggesting Chubb had a "pretty bad heroin problem" at the time and was desperate for money.

During his testimony, Chubb answered many questions with "it's possible," leading Ritchie at one point to tell him that was not a helpful answer. 

Chubb responded by saying it had been a number of years, and after a head injury he received he was not good with dates.  

Ritchie ended the day telling the court he was still going to be "awhile" with Chubb, who will continue on the stand Wednesday.  

Pickton is facing 26 counts of first-degree murder in connection with the deaths of women from Vancouver's Downtown Eastside. Six of the charges are being dealt with at the current trial. The other 20 charges are expected to be dealt with at a subsequent trial.