Posted Wednesday, June 20, 2012 --- 2:41 p.m.

MADISON, Wis. (AP) -- An online weapons dealer who supplied three mass killers has quietly closed up shop amid numerous customer complaints.

Eric Thompson's Green Bay-based company, TGSCOM Inc., sold a handgun Seung-Hui Cho used in his 2007 attack on Virginia Tech students. The company also sold accessories to George Sodini, who shot up a Pennsylvania health club in 2009, and to Stephen Kazmierczak, who opened fire at Northern Illinois University in 2008.

Police say Thompson closed the business at the end of May after scores of customers complained they ordered equipment and received nothing. The Wisconsin Better Business Bureau says it has received nearly 200 complaints from customers in 44 states since January. Detectives have opened an investigation.

Thompson did not respond to multiple attempts to reach him.

Copyright 2012: Associated Press