She emphasized that Augustine could have been injected in an another part of her body with no needle track left.

"A good nurse could have delivered it in a manner I did not detect," she said.

Higgs, a critical care nurse, has been charged by Washoe County authorities with murdering his wife by injecting her with succinylcholine, a powerful muscle relaxant used in hospital emergency rooms.

During other testimony Friday, two nurses at Washoe Medical Center's South Meadows branch called Higgs, 43, an excellent nurse with good patient skills. They also testified that succinylcholine was available for use by emergency room nurses and that a determined nurse could remove it undetected from the hospital.

Higgs could receive life in prison without parole if convicted. The case is one of a handful nationally and the first in Nevada in which prosecutors contend succinylcholine was used to kill.

Clark's testimony about an undetected injection site is important because Higgs lawyer Alan Baum maintained Thursday that the state's case is based on the theory Higgs injected Augustine in her left buttock with the lethal drug.

Clark said Friday there was a slightly better than 50 percent chance the mark on her buttocks was from a needle.

Deputy Washoe County District Attorney Christopher Hicks challenged Baum's portrayal of the state's theory.

"We have never said that was the sole point where he injected her," Hicks said in an interview. "We are saying he injected her with succinylcholine."

Despite repeated assertions by Baum that Augustine could have died from sudden heart failure, Clark maintained as strongly that her death was caused by the drug. She noted she has performed 4,000 to 5,000 autopsies in a career dating back to 1989.

Clark also challenged statements made Thursday by Dr. Anton Sohn, director of the department of pathology at the Nevada School of Medicine.

Sohn said Higgs could not have injected Augustine because the puncture mark was too fresh and would have been made during the time she was in the hospital.

"I disagree anyone can be that precise on dating," Clark said.

South Meadows nurses Tina Carbone and Katharine Amaraz said Friday they noticed Higgs was becoming increasingly bitter because of his marital problems with Augustine.

They testified that she was a jealous woman who harassed and threatened them and sometimes disrupted their work by showing up unannounced in the emergency room. At times, she even demanded his paycheck.

Carbone said she filed a complaint against Augustine with the state Ethics Commission. Amaraz, who has served on domestic violence organizations, said Higgs appeared to be an abused spouse.

Both nurses said Higgs often would confide in them at work about his marital problems. They said the couple's marriage seemed to deteriorate when Augustine became the first state official ever impeached. She was fined $15,000 for state ethics violations, but allowed by the state Senate to remain on as state controller in December 2004. She was running for treasurer at the time of her death.

The prosecution will end its case Monday.