Bobbi-Jo Vader believes her brother is innocent, and she did everything she could on the witness stand Friday to try to protect him.  

Travis Vader is charged with the first-degree murders of Lyle and Marie McCann in July 2010.  

"I do believe my brother's innocent," his younger sister testified. "And I will stick up for him any way I can."  She hastily added, "While telling the truth."

Crown prosecutor Ashley Finlayson was granted permission by the judge to cross-examine Bobbi-Jo Vader as a hostile witness. He was allowed to grill her on inconsistencies between her sworn testimony on Thursday and statements she gave to RCMP in 2010.  

On July 16, 2010, Bobbi-Jo Vader told investigators she'd noticed a drastic change in her brother over the previous two years.

"He went from having everything, to nothing," she said. "No Job. Nothing. He lost his family, he lost his job, he's lost a lot of his friends. He's hanging out with people that are into crime. He's into meth. He calls himself a cook. He's lost tons of weight. He's not the same."

Undering questioning Friday, she repeatedly insisted the statements she made to RCMP could not be trusted, because she was addicted to crack cocaine at the time. She testified she went on binges that would last for up to five days, then sleep for two days before repeating the cycle.

She said it was "possible" she was high on drugs when she was interviewed by RCMP, but after watching and listening to her interviews in the courtroom, she admitted she "appeared to be functioning normally."  

During one interview, she admitted to an officer that she was a crack addict. "Just because I'm a user doesn't mean I'm not a reliable witness," she said.

On the witness stand, she admitted, "Everything I told him, I thought was true in my head."

Lawyers hotly contested the truth of one specific statement she made to RCMP. In August 2010, she was asked about the presence of guns in the back of her brother's truck when he visited her in Edmonton on July 4, 2010. He's accused of murdering the McCanns the day before.

'I do not touch firearms' 

More than five years ago, she told the Mounties, "I know that there were firearms in there. But I don't know what they were. I didn't see them personally. All I know is that they were in the back wrapped up in blankets. And I do not touch firearms. My brother knows that."

She told Mounties she knew about the weapons because her brother had warned her about them.

But on the witness stand, she tried to distance herself from her 2010 statement, once again blaming drugs and lack of sleep.

The prosecutor pushed her.  

"You knew Travis was being investigated," Finlayson said. "The last thing you would have wanted to do at that point is to make something up and make the situation worse."

Bobbi-Jo Vader finally conceded it would have made no sense for her to have told the RCMP about the guns had the statement not been true.

She testified she became so worried about her drug use in the fall of 2010 that she sought the help of an addiction counsellor and got clean.  

But she told defence lawyer Brian Beresh she relapsed a year later, when she became the target of a so-called Mr. Big operation, designed to gather evidence against her brother.  

She admitted she was paid thousands of dollars by undercover RCMP officers for "not doing a lot," and used the cash to get drunk and high, even though she had court conditions ordering her to abstain from drugs and alcohol.  

Based on court documents, CBC reported late last year that Bobbi-Jo Vader told undercover operatives that "she believed that Travis was involved in the murders and she saw guns wrapped up in blankets that could have come from the McCanns' motor home."  

The prosecutor did not ask Bobbi-Jo Vader any questions about the Mr. Big sting, and the defence only mentioned it in reference to her relapse.  

janice.johnston@cbc.ca

@cbcjanjohnston