NEW WESTMINSTER, B.C. - When accused serial killer Robert Pickton didn't understand something, he would sometimes just walk away from the conversation, a jury heard Wednesday.

And when doctors told him in 1999 that he'd contracted Hepatitis C, he didn't seem to understand the seriousness of the disease.

The defence team at Pickton's trial for six counts of first-degree murder changed tack mid-witness Wednesday, dropping questions about Pickton and his brother Dave's business ventures and heading straight for what they had earlier said would be one of their major arguments -- the accused's level of intelligence.

Sandy Humeny's low, gravelly voice rumbled through the courtroom as she described how she'd talk to Pickton about business and other matters.

"When when we would talk, it would have to be very plain and clear, none of the words could be too elaborate or too above, his vocabulary was very minimal,'' said Humeny, a former common-law partner of Pickton's brother Dave.

She said a look would come over Pickton's face when he didn't understand what his co-workers were saying and he'd switch topic suddenly or walk away.

"Many times where I've seen that happen, even if they were joking around, he did not get the joke, he did not get the punchline,'' she told defence lawyer Adrian Brooks.

Humeny, who dropped out of school at 16 with only a Grade Eight education, moved onto the Pickton property in 1973 with Robert's younger brother Dave.

She lived there for five years, and she and Dave Pickton had a daughter, then a son.

Humeny, 51, remembered how the brothers' mother, Louise, ruled the roost as their father Leonard fell prey to the mental ravages of time.

Louise Pickton would delegate tasks to the brothers, Humeny and the various hired hands who lived in the house.

Humeny told court how she'd see Dave and his mother talking over finances and business matters, but Robert was never part of the conversation.

When Louise Pickton died, Dave took over.

"He delegated the work and we did it,'' Humeny said.

Though Humeny and Dave split up in 1978, she worked on and off for him for years, most recently taking a job with his topsoil and demolition company in 1996.

She'd go by their house to visit with the kids or drop off paperwork for the brothers. For Dave, it was business invoices and contracts, for Robert it was auction invoices and notices of upcoming sales.

Robert Pickton was often around the farm, either in his trailer or out working on vehicles or by the piggery.

Humeny was part of a job on a CostCo site in 1999 where the brothers and other workers worked demolishing and refurbishing the store all night for weeks at a time.

Pickton is on trial for killing six Vancouver women who disappeared from the Downtown Eastside beginning in the late 1990s.

He is to stand trial on 20 other counts of murder at a later date.

He contracted hepatitis C in 1999 and went on medications that made him tired, Humeny said.

But when she talked to him about the disease, which can cause liver disease and cancer, he didn't know much about it, court heard.

"He didn't realize he really honestly did not realize the depth of it, the depth of the seriousness of hep C,'' Humeny said.

When the defence opened their case earlier this month and in their brief opening arguments when the trial began last January, they asked the jury to pay close attention to Pickton's level of intelligence and apply what they were to hear to the statements he made to police following his arrest in 2002.

During an eleven-hour interview with police, Pickton told them he'd gotten sloppy and had planned to do one more before stopping.

Later, to an undercover officer in his cell, Pickton suggested more killings were planned.

"I was going to do one more, make, make the big five O,'' he said, then later added: "So let everything die for a while. Then, then do, do another 25 new ones.''

But he also regaled his cell mate with a fanciful story about how he lived in a chicken coop when he was 2 1/2 years old and drank water out of a stream that ran through the coop.

The stories led the defence at the time to challenge the cell plant on whether he thought perhaps he was dealing with a simple man.

Brooks had also told the jury to think about what a man who was facing multiple murder charges would do following his arrest and contrast it with what Pickton did.

On Wednesday, jurors heard that after his initial arrest in February 2002, Pickton went to work.

Humeny testified the crew was working a demolition site in Steveston, B.C., just outside of Vancouver, and Pickton was on the crew.

The trial bogged down in legal arguments for the remainder of Wednesday.

Earlier, the jury had heard more testimony about the comings and goings from the Pickton property, where the remains of the six women were found.

Around six o'clock in the morning each work day during the spring and summer months, Lorne Loewen would knock on Pickton's trailer and get his work day started.

They'd have a quick conversation and Loewen would get to work, picking up faxed invoices for the topsoil delivery business.

Loewen, 46, gave similar testimony to earlier witnesses who had described the farm as being a constant beehive of activity.

"Sometimes it looked like a yard sale,'' Loewen told the court. "People coming, asking to buy cars and topsoil.''

When he was working on the Pickton farm, court heard, Dave would ask Loewen to keep the gates locked to combat a problem with theft and stop the constant flow of people onto the farm.

"People coming in and out, sort of undesirable people, coming in cars, trying to sell you something or looking for Willie,'' said Loewen, who started working for the business in 1996 and remains an employee.

Loewen told court he'd buy cars from Robert Pickton that had come from auctions held by the Vancouver police department.

He described the cars as looking like people had lived in them, filled with food wrappers, needles and bags of clothing.

Pickton is on trial for the deaths of Sereena Abotsway, Marnie Frey, Andrea Joesbury, Georgina Papin, Mona Wilson and Brenda Wolfe.