ELLSWORTH, Wis. (WCCO) — Testimony resumed today for the Wisconsin mother charged with negligence in a traffic accident that killed her daughter and two nieces.

Prosecutors will try to prove that Kari Milberg was posting messages on her cell phone in the minutes just before the crash. Milberg was driving the children on a western Wisconsin road in December 2013 when she was hit by an oncoming truck.

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On Tuesday, jurors heard about road conditions, poor tires and what was found on her phone.

There are two very different opinions of how the crash happened. The prosecution says Milberg was distracted by her cell phone. The defense is trying to show investigators did a poor job, ignoring the slippery road conditions and bad tires.

The day began with the defense picking away at a sheriff’s department investigator, Doug Ducklow, suggesting the tires on Kari Milberg’s car were too worn to be safe on any pavement.

“I wasn’t qualified to give any suggestion about those tires,” Ducklow said.

Jurors then heard a recording of the truck drivers involved. Two brothers said conditions were slippery, saying it appeared the Milberg car lost control.

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The prosecution is out to prove Milberg was Facebook-messaging on her phone just before the crash, and drifted into the path of the oncoming truck, killing her 11-year-old daughter and two young nieces.

Investigator Aaron Hansen found Milberg’s phone four months later, after snow had melted. He describes a Facebook chat log, detailing a string of messages between Milberg and Jason McKenzie. They were planning lunch and joking about being nervous.

When McKenzie took the stand, he was uncooperative and couldn’t recall even messaging Milberg.

“I just heard there was an accident,” he said.

Evidence shows the final exchange came, 19 seconds before the 911 call.

When Milberg’s phone was located the service no longer worked. When it was first charged, the Facebook app popped onto the screen and quickly disappeared, so investigators couldn’t tell if Milberg had a message typed in but hadn’t sent before she crashed.

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A State Patrol mechanical inspector also tested Milberg’s car and determined that the brakes and steering all worked. There was a missing wheel lug and sway bar link was broken. While he noted that the tires were badly worn, they were still legal.