GRAND HAVEN, Mich. (NEWSCHANNEL 3) - Friday was day four in the trial of the man accused of killing four people in Wright Township.

Prosecutors say Troy Brake killed Sharmaine Zimmer, her sons Jeremy and Tyler, and Jeremy's girlfriend Katherine Brown. All four victims were found inside a burned out home in Wright Township in September.

Thursday, the court got a tour of the grizzly scene where the bodies were discovered, and Friday, part of the testimony came from someone very close to Brake, someone who could make or break his defense.

The case could very well hinge on the believability of one Tara Van Dyke, Brake's girlfriend.

She wants jurors to believe her when she says that Brake was home when the crime was committed, but prosecutors say her story simply doesn't make sense.

Prosecutors shot rapid-fire questions at Van Dyke, trying to pin down a definitive time line for the night of the crime. Van Dyke says Brake came home at 11:30 the night the murders occurred, important testimony because prosecutors believe the crime was committed just before midnight. That means Van Dyke is a possible alibi for Brake, but prosecutors believe that she is not telling the truth.

"You're telling this jury under oath that absolutely, Troy Brake was home at 11:30 that night, is that correct?" asked prosecutor Ran Frantz.

"Yes," said Van Dyke.

Prosecutors were able to point out inconsistencies in some of Van Dyke's testimony Friday. She said Brake left his house in Newaygo County at 9:30, when phone records show it was 10:15. Van Dyke had also originally told detectives that Brake didn't get home until 12:30, perhaps even as late as 1:30 in the morning, but changed her story to 11:30, saying her memory got better with time.

The prosecutor suggested that Van Dyke is under pressure to lie in the case, with that pressure coming from family members of Brake.

Brake's loved ones are currently paying the mortgage on the house where Van Dyke lives in Grant. Van Dyke told jurors she wasn't being forced to change her story.

"You make it sound like if they didn't pay for the house I'd be out on the street," said Van Dyke, "I don't have to live there."

Earlier in the week, Van Dyke and Brake's system had walked away from Newschannel 3 cameras as we attempted to question them about the change in time line.

Van Dyke also testified on Friday that Brake came home smelling of smoke the night of the murders, and that it was a weird smell.