Jurors began deliberations Tuesday in the trial of a man accused of using antifreeze to poison his wife, who left a note saying he should be a suspect in the event of her death.

Mark Jensen, now 48, is charged with first-degree murder and faces a maximum penalty of life in prison without parole if convicted.

In closing arguments Monday, attorneys on each side said there wasn't enough evidence supporting the other's theory about the way Julie Jensen, 40, died in her Pleasant Prairie home in 1998.

Prosecutor Robert Jambois said Mark Jensen plotted to kill his wife, searching the Internet for information on ethylene glycol -- commonly used as antifreeze -- and then giving her sleeping pills and making her drink juice he had spiked with the toxic chemical.

When her health appeared to improve, he pushed her face in a pillow and suffocated her, Jambois claimed.

Defense attorney Craig Albee said the prosecution's case relied on questionable witnesses -- jail inmates, a poison expert who made a crucial mistake and witnesses whose memories had faded after nearly a decade.

Albee said defense experts proved that Julie Jensen was depressed and committed suicide.

Julie Jensen had left a letter with a neighbor, in which she wrote: "I pray that I am wrong and nothing happens, but I am suspicious of Mark's suspicious behaviors and fear for my early demise." She told the neighbor to give the letter to police if she died.