PONTIAC, Mich. -- A school teacher hacked her husband to death in a deliberate attack and then took elaborate steps to cover up the crime, a prosecutor told jurors Tuesday.

But a defense attorney said his client, Nancy Seaman (pictured, left), was a victim of decades of spousal abuse and acted in self-defense when she killed her husband, Robert.

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"Bob Seaman died a gruesome death," assistant county prosecutor Lisa Ortlieb said during her opening argument in an Oakland County courtroom. "The defendant had time to think about what she was doing. ... She chose to be a killer."

Defense attorney Lawrence Kaluzny told jurors Seaman endured 30 years of on-and-off physical and emotional abuse which had intensified in the months preceding the killing in May.

"Nancy thought she was going to die that day," Kaluzny said.

The defense attorney said Robert Seaman (pictured, below) attacked his wife, who grabbed the first thing she saw to defend herself -- a hatchet she had bought for yard work.

Lawyers chose a jury Monday to hear the murder case against Nancy Seaman, a former fourth-grade teacher at Longacre Elementary School in Farmington. Seaman is accused of killing her husband with a hatchet, knife and sledgehammer.

The jury began hearing the case Tuesday when the lawyers made their opening statements. Following those, graphic photos of Robert Seaman's corpse were shown to jurors, some of whom winced when they saw them. L.J. Dragovic, the county medical examiner, described Robert Seaman's wounds as the photos were shown.

An autopsy revealed that Seaman was stabbed more than 20 times. A knife found with the body is believed to be the murder weapon, police said.

The couple's son, Jeff, testified that he never saw any physical abuse and that his parents had been arguing quite a bit in the time leading up to the killing. Jeff Seaman, a 25-year-old who lives in Wayne County's Brownstown Township, said his father had been sleeping in the basement.

He also testified that his mother was buying a condominium earlier this year unbeknownst to her husband. It was clear to those who knew the couple that they eventually would separate, Jeff Seaman said.

Officers found Robert Seaman's body on the afternoon of May 12 in the back of a Ford Explorer parked in the driveway of the couple's home on Briarwood, near 13 Mile Road and Halstead in Farmington Hills. He had reportedly been dead for several days.

Police say Nancy Seaman attempted to cover up the crime and went to work one day after she allegedly killed her husband, the station reported.

Police believe the teacher wrapped her husband's body in a tarp, secured it with duct tape and then placed it in the back of the SUV, according to Local 4 reports.

When officers questioned her about the large object in the back of the Explorer, she allegedly told them it was artwork.