Quarterback Steve McNair of the Baltimore Raves drops back to make a pass on January 13, 2007. ((Doug Pensinger/Getty Images) )

Former NFL quarterback Steve McNair was killed by girlfriend Sahel Kamezi before the 20-year-old shot herself in the head, police confirmed Wednesday.

The wife of the former football player, Mechelle McNair, didn't know her husband was having an affair with Kamezi until their bodies were found lying together, said Mike Mu, who has done charity work with McNair.

McNair, 36, was found dead on July 4. He'd been shot four times.

Assistant medical examiner Feng Li confirmed Wednesday gunpowder residue was discovered on the hands of Kamezi. She was found with a single gunshot wound. A gun she had purchased two days earlier was under her body.

Further test results on the weapon and toxicologies are still pending.

A funeral service for McNair will be held Saturday in Mississippi.

Mu, who's fielding media inquiries for Thursday's memorial service, said Mechelle "didn't know who this girl is." No divorce proceedings have surfaced.

Mechelle McNair hasn't spoken publicly since the shooting. Those close to her, however, have said she's distraught.

Police say it might never be known what Kazemi was thinking when she shot McNair in his condominium Saturday morning. He was reportedly asleep on the couch. He rented the condo with another man.

Investigators say friends of Kazemi revealed she was becoming increasingly distraught over various events in her life, including financial struggles. Police also said she thought McNair was seeing another woman.

"We do know that she was clearly sending a message during the last five to seven days of her life that things were going bad quickly," said police chief Ronal Serpas.

However, she didn't tell anyone she wanted to harm McNair, Serpas said.

Two days before the murder, Kazemi was stopped by police while driving the Escalade given to her by McNair for her birthday in the spring.

Police records indicate Kazemi had bloodshot eyes and alcohol on her breath. She was charged with DUI after insisting she wasn't drunk but "high." McNair was with her at the time and later paid to bail her out.

The close friend who reported McNair's death to 911 spoke to a Tennessee newspaper and lashed out at those making negative comments about his former teammate.

Robert Gaddy said the McNairs' Nashville home was for sale because the family was intending to move.

"People need to quit talking about what they don't know," Gaddy told the newspaper. "Mac never said anything to me about he was going to get a divorce, and ever since this has all happened everybody is trying to paint a certain picture, and they need to talk about what they know."

On Wednesday, the four-time Pro Bowl quarterback was being recognized at the stadium where he played much of his career.

The Tennessee Titans opened LP Field for fans to watch video highlights of McNair's 13-year NFL career. Photos of McNair were also on display, and fans could write messages to the family in a book.

Mechelle McNair met her husband when they were university students. She later studied nursing in Nashville while he played for the Titans. The pair married in 1997 and had two children. Steve McNair also has two other children.

With files from The Associated Press