JOLIET, Ill. (CBS) — Will County prosecutors are nearly done presenting their case at the murder trial of Christopher Vaughn, the Oswego man who’s accused of killing his wife and three children.

As WBBM Newsradio’s Regine Schlesinger reports, prosecutors have been presenting evidence to contradict Vaughn’s version of what happened that day five years ago, when his wife, Kimberly, and their three children were found shot to death in their sport-utility vehicle on a road near Channahon.

LISTEN: WBBM Newsradio’s Regine Schlesinger reports

Vaughn maintains Kimberly Vaughn shot him, and after he ran to get help, she killed the children and then herself.

A ballistics expert testifying for the prosecution Monday said the crime scene was not consistent with that story, just as last week, a forensic scientist said the blood stains did not support that account.

On June 14, 2007, Vaughn, his wife, and their three children – Abigayle, 12; Cassandra, 11; and Blake, 8, were on their way to a water park in Springfield from their home in Oswego.

Prosecutors say Vaughn shot pulled off Interstate 55 in Channahon Township and stopped on the frontage road. Then, authorities say, he shot his entire family inside their Ford sport-utility vehicle.

Vaughn’s wife was shot in the head, and each of his three children were shot twice. Vaughn himself suffered minor gunshot wounds in his wrist and leg.

Days later, Vaughn was arrested at the funeral services and charged with murder.

Vaughn and his defense team claim his wife shot the children and even fired at her husband’s head – only for the bullet to be deflected by his watch – before turning the gun on herself.