Changes were made to Zoeller's biography on the site which said that he was addicted to alcohol and pain killers. They said that while under the influence of these he beat his wife and his four children. The offending words have since been removed.
Zoeller has filed a lawsuit alleging that the posts were defamatory. The IP address of the poster has been traced to Josef Silny & Associates, a Miami educational consultancy whose owner, Josef Silny, says he knows nothing about the postings.
Silny told reporters in the US that he was working with his IT department to attempt to identify who in his office, if anyone, had written the posts.
Wikipedia is an encyclopaedia which anyone is permitted to edit, in contrast to traditional encyclopaedias which are researched, written and independently checked by experts in each particular field.
Though Wikipedia is one of the biggest successes of the trend towards user-generated content, it has often been caught up in legal controversy because of the unfiltered nature of the material posted there.
Wikipedia's advocates say that it is to an extent self-policing because so many people use and edit it that obvious or malicious errors are corrected quickly. Critics say that it is a useful tool for partisan political activists or those wishing to spread misinformation to distort what is read as the truth.
The once-completely open site has introduced security measures. Some pages dealing with sensitive issues are locked completely, while others can only be accessed by people who have completed a probationary period of postings. The IP address of a non-registered user who makes changes to a page is displayed in that page's edit history.
Wikipedia is not liable for the remarks, Scott Sheftall, Zoeller's lawyer, told the Associated Press news agency. "Courts have clearly said that you have to go after the source of the information," he said. "The Zoeller family wants to take a stand to put a stop to this. Otherwise, we're all just victims to the internet vandals out there. They ought not to be able to act with impunity."
