Two brothers of a dentist whose wife was found shot to death in their home are scheduled to appear before a Gwinnett County grand jury Wednesday.

The brothers are expected to talk about the whereabouts of Barton Corbin (search) the night his wife, Jennifer, was killed.

The brothers are among four people subpoenaed by District Attorney Danny Porter.

The prosecutor confirmed Tuesday that authorities are investigating that Jennifer Corbin (search) was corresponding with a Missouri man she met on the Internet.

Barton Corbin had filed for divorce and was seeking custody of the couple's two sons, ages 7 and 5.

Corbin's lawyers said at a news conference Tuesday that he is innocent and cooperating with police. Corbin has submitted to a gunfire residue test, but he has yet to be questioned by investigators.

One of the Corbin's sons found Jennifer Corbin's body early on Dec. 4 in their home in Buford.