Mark Schwarz reports from New Orleans, where the testimony of Will Smith's accused killer, Cardell Hayes, took a hit after witnesses contradicted his claim of self-defense. (1:36)

NEW ORLEANS -- If the man accused of murdering former Saints standout Will Smith is going to take the stand in his own defense, Saturday will probably be the day, now that the prosecution has rested its case.

Cardell Hayes is claiming he shot and killed Smith in self-defense on the night of April 9, after a heated argument ensued between their two parties following a pair of traffic incidents.

On Friday, the prosecution's fourth and final day of testimony included experts who testified that Hayes intentionally crashed into Smith's vehicle and that evidence did not support the theory that Smith was reaching into his car at the time he was shot. After the prosecution finished, the defense began presenting its case Friday afternoon.

The prosecution finished its case by calling former New Orleans police captain Billy Ceravolo, a close friend of Smith's who became a highly publicized figure in the weeks after Smith's shooting when defense attorney John Fuller suggested Ceravolo might have tampered with evidence at the crime scene.

Ceravolo adamantly denied those claims Friday and was critical of his reputation being sullied so publicly. The state had earlier shown video evidence that proved Ceravolo was not on the scene at the time of the shooting. Ceravolo was called to the scene afterward by Saints running back Pierre Thomas, a mutual friend of Smith's and Ceravolo's who was out with them that night.

Ceravolo's possible involvement continued to be debated as the defense began its case with a private investigator, David Olasky, who testified about a female witness who told him she thought she saw Ceravolo reach across Smith's body toward the glove compartment and pull out what she thought was a gun. The state, however, got the detective to acknowledge that the witness was wrong about Ceravolo being there at the time.

"Some things about her story were true, some things she might have gotten wrong or confused. ... [But] I believe she saw someone removing something from the area of the glove box," Olasky said.

The defense also called a crime lab deputy, Madelyn Collins, to testify that gunshot residue was found on Smith's hands, explaining it could possibly have come from firing a gun, from being near a gun when it was discharged, or from touching a gun that had been discharged. The state, however, had her specify that she found only two particles on the back of each hand and one on the left palm -- for a total of five particles -- but none on the right palm, and that it's possible residue could come from a gun being fired into his vehicle.

The defense has been hinting at the possibility that Smith might have held or fired a gun that was removed or moved at the scene, though Olasky is the only one to testify about anyone having seen such activity.

Homicide detective Bruce Brueggeman testified Thursday that Smith's gun was found holstered with the safety on, wedged between the driver's seat and the center console.

The defense finished the day by calling character witnesses who described Hayes' calm demeanor earlier that night.

Perhaps the most impactful testimony Friday came from the two expert witnesses at the beginning of the day, according to multiple media accounts.

Car crash expert Michael Sunseri says he put the blame for the crash squarely on Hayes, though the defense challenged Sunseri's conclusions based on "black box" data from the Hummer and Smith's Mercedes SUV. Defense attorney Jay Daniels suggested Hayes might not have been paying attention and thus hit Smith's vehicle by accident.

Also, Dr. Samantha Huber, the chief forensic pathologist for the Orleans Parish Coroner's Office, testified that the first shot hit Smith from a level angle and into his left side, which indicates he wasn't reaching into his car for a gun as the defense has suggested.

Smith was shot a total of eight times, first in the side and the next seven in the back as his body wound up slumped across the driver's side of his vehicle. Before that, his wife, Racquel, was shot through both legs while she was in close proximity to her husband, trying to pull him away from the heated argument, according to multiple witnesses.

The defense is claiming that Smith had either threatened to get his own gun or had already retrieved it before Hayes began shooting at him. Multiple witnesses for the prosecution claimed that Smith and Racquel were walking away after she had successfully calmed him down.

The defense is claiming that Smith and members of his party were acting as the aggressors in the confrontation that followed Hayes crashing into Smith's vehicle. Huber also confirmed that Will Smith's blood-alcohol level registered at .235 percent, nearly three times the legal driving limit, which had been previously reported.

Racquel Smith left the courtroom briefly, audibly sobbing, while the pathologist was describing each of the gunshot wounds that Smith suffered and the damage they caused.

The Associated Press contributed to this report.