The edit was made a minute past midnight Eastern Time. It was an anonymous edit from the IP address 184.108.40.206 using the Internet service provider Optimum Online. The IP was traced to a (so far) anonymous user originating in Stamford, CT, which of course is the headquarters of World Wrestling Entertainment. Then just one hour later after the first edit reversion, another anonymous edit by 220.127.116.11 using unwiredAustralia.com.au, a wireless Internet service provider, was made adding about the aforementioned personal issues: “which according to several pro wrestling websites is attributed to the passing of Benoit’s wife, Nancy.” That edit was reverted just under 20 minutes later, with the comment: “Saying ‘several pro wrestling websites’ is still not reliable information.” Further investigation shows that the IP address used to make the first edit is located in Connecticut, but the IP address is not linked to any computers or servers used by the WWE. The second edit was made by a computer in Australia from a wireless network.
You can see the Wikipedia edit in question at en.wikipedia.org/w/index.php?title=Chris_Benoit&diff=140442953&oldid=140425583. If you have a Wikipedia account set to EST, it says “Revision as of 00:01, 25 June 2007”.
WikiNews.org also has more on this story.