New Haven - A Connecticut man charged with a gruesome home invasion had gas on his boots, pants and sweatshirt, a state lab official testified Monday, potentially undermining defense efforts to blame a co-defendant for dousing the house in gas and setting it on fire.

Prosecutors finished calling witnesses Monday in their case against Joshua Komisarjevsky, who faces a possible death sentence if convicted of the July 2007 attack on a family in its Cheshire home. His co-defendant, Steven Hayes, was convicted last year and is on death row.

Authorities say Komisarjevsky and Hayes broke into the Petit family's home, beat Dr. William Petit with a bat and tied up him and his family. Hayes was convicted of raping and strangling Petit's wife, Jennifer Hawke-Petit, and killing the couple's two daughters, who died of smoke inhalation.

Komisarjevsky had gas on his clothes, testified Jack Hubball, a chemist at the state forensic lab. Komisarjevsky has blamed Hayes for pouring the gas.

Michaela Petit, 11, who was killed in the fire along with her 17-year-old sister, Hayley, had bleach on her shorts, Hubball said. Komisarjevsky is charged with sexually assaulting the girl. Hayes' attorney said during his trial that Komisarjevsky had poured bleach on her clothes to try to eliminate his DNA.

The girls and their mother all had gas on their clothes, Hubball said.

Under cross-examination, Komisarjevsky's attorneys noted he did not have gas on the gloves he wore and suggested the fuel could have come from construction work Komisarjevsky did.

During two weeks of testimony, prosecutors played an audiotaped confession in which Komisarjevsky spoke matter-of-factly and laughed occasionally. He admitted beating Petit with a bat and molesting his younger daughter, but insisted Hayes wanted to kill the family because he was worried about his DNA at the scene.

The judge stopped the tape early one day just after Komnisarjevsky admitted molesting the girl, saying a juror was having a tough time. Jurors saw grim evidence, including charred beds, rope used to tie up the family and autopsy photos.

Hayley likely took up to several minutes to die, a medical examiner testified. Dr. Malka Shah could not say if burns found on Hayley's body occurred before or after she died. Gas was poured on her bed and on her sister, according to testimony.

William Petit took the stand, describing how he fell, crawled and rolled in his frantic escape to a neighbor's house to get help.

The defense is expected to take about a day when the trial resumes Wednesday. Komisarjevsky's attorney portrayed him in their opening statement as panicked and indecisive, claiming he suffers from "cognitive difficulties" that leave him unable to make quick decisions in stressful situations.

During the trial, Komisarjevsky often leaned back in his chair and occasionally made eye contact with jurors. Hayes sat huddled, mostly looking straight ahead. He lost substantial weight after the crime and his attorneys claimed he was remorseful and suicidal.

A judge denied a defense motion for a mistrial earlier Monday after a supporter of the victims' family spoke to jurors.

A juror says a member or supporter of the Petit family commented Friday during the lunch break, saying "thank you for doing what you're doing." The judge then questioned the jurors about what was said and how it affected them.

Two alternate jurors were nearby but said they didn't hear the comment. None said the comment affected his or her ability to serve impartially.

Judge Jon Blue called the comment improper but not catastrophic.

Walter Bansley, Komisarjevsky's attorney, noted he had sought unsuccessfully to have the trial moved out of New Haven. He said the comment was aimed at influencing jurors.

"This just highlights the extraordinary pressure that surrounds this case," Bansley said.

He said the defense has had difficulty getting witnesses to cooperate because of perceived and actual intimidation. Bansley said a defense supporter was approached on the first day of the trial by a Petit family supporter who said: "How dare you support him. You disgust me."

The same person had a dead mouse left in his mailbox, Bansley said. He also said members of lawyers' families have been threatened.

"It's this atmosphere that permeates the whole trial," Bansley said. "It's certainly clear to the defense Mr. Komisarjevsky cannot get a fair trial."

Blue warned that he would ban anyone from the court for approaching jurors.

Johanna Chapman Petit, aunt of the two girls killed, said she wasn't sure who approached the jurors but was sure no family member did. She said she didn't think anyone was trying to influence jurors.