Philip Chism’s attorneys admit the teenager killed his math teacher, Colleen Ritzer. But his defense team: "see an advantage in questioning the evidence in the case.

Chism's attorney’s are asking witnesses very specific questions about the evidence – for example, they had an officer confirm he saw blood on a shoe, but not the ground around it.

WGBH Legal Analyst Daniel Medwed says the defense may be trying to demonstrate Chism’s actions weren’t premeditated. 

“The defense is trying to show there are a lot of loose ends here. That he didn’t take pains to make it the ‘perfect crime,’ and therefore it’s a sign of somebody who didn’t really have a sense of the consequences,” said Medwed.

Prosecutors, meanwhile, are piling on the evidence. They’ve shown footage of Chism following Ritzer into a bathroom and coming out alone. And they’ve brought in the green recycling bin Chism allegedy used to move Ritzer’s body.

Chism may have killed Ritzer, but jurors will have to decide if the evidence points to first degree murder.