A "normal man living a normal life" turned into a killer in November 2007 when he found out his wife was having an affair, a prosecutor argued Monday in Lancaster County Court.

The "hurt and angry husband" — 30-year-old Shannon Hess — responded to the betrayal by fracturing his mother-in-law's skull, then repeatedly slashing her neck during a fit of rage, the jury was told.

Hess was bitter that his wife was sleeping with his boss and that his mother-in-law, Barbara Fritchman, was taking sides with the other man, the prosecutor said.

During the first day of Hess's trial, jurors were shown the graphic consequences of a jealous husband who bludgeoned Fritchman with a tool, then stabbed her at least seven times with a knife, according to prosecutors.

Some jurors cringed as they looked at photos of the 45-year-old Fritchman facedown in a pool of blood inside the family's Willow Street home.

"The anger, rage and frustration got the better of him," Assistant District Attorney Mark Fetterman said in his opening statement.

Hess, now 31, is charged with criminal homicide for the killing at 53 E. Boehms Road in Pequea Township.

Defense attorney Alan Goldberg deferred his opening statement until later in the trial.

Fetterman described a love triangle involving Hess, his wife, Veronica, and Bill Frank that ended in the killing. Fetterman said Hess was the "last to know" about his wife's affair, long after rumors began swirling around a Leola mobile home business, where the trio worked.

Eventually, Fetterman argued, Veronica Hess confessed to the affair and Frank also came clean.

"The secret's out," Fetterman said, "and things started to unravel."

Shannon Hess wanted to reconcile for the sake of the couple's two children, but his wife had other plans. She wanted to move out and take the children with her, according to Fetterman.

Hess had been spying on his wife Nov. 23, 2007, before returning home to find Fritchman on the phone with Frank, the prosecutor said.

Fetterman argued that's when Hess snapped. He killed Fritchman, then tried to clean up the crime scene before a baby sitter called and asked Hess to pick up the children, Fetterman said.

When Hess returned home with the children, ages 4 and 9, he told them to run to a neighbor's house while he called 911.

Prosecutors played the 7-minute recording of that 911 call.

"I think my mother-in-law's dead," Hess tells the dispatcher. "I haven't checked her pulse or anything, but there's blood everywhere."

Hess sounded exasperated during the call, repeatedly describing the graphic scene while telling the dispatcher he didn't know what happened to the woman.

"(Blood's) everywhere. It's on the walls, and she's laying in it. It's like a puddle." Hess says on the recording. "I don't know what to do."

Also Monday, Fetterman called to the stand the first three Southern Regional police officers who arrived at the house and a detective who took photos of the grisly scene.

Fetterman told jurors the trial could last two weeks, with testimony expected from Frank, other co-workers and friends and family.

He asked jurors not to be swayed by Hess's reputation as a "nice guy" or to pity him as a betrayed husband.

"He's not on trial for who he is. He's on trial for what he did," Fetterman told the jury.

Hess, dressed in a gray suit, listened attentively to witnesses and attorneys. He showed little emotion, but ground his teeth and blinked hard when the 911 recording was played.

Testimony before Judge Jeffery D. Wright continues this morning at 9.

E-mail: bhambright@lnpnews.com