Conversation so far:
Did Brown commit copyright infringement?
In August 2005 author Lewis Perdue unsuccessfully sued Dan Brown for plagiarism.
Did Dan Brown write novels?
In 1996 Dan Brown quit teaching to become a full-time writer. Digital Fortress was published in 1998.
What other novels did Dan Brown write besides Digital Fortress?
Dan Brown also co-wrote a humor book with his wife, 187 Men to Avoid: A Survival Guide for the Romantically Frustrated Woman.
Were there other copyright cases besides Lewis Purdue suing Dan Brown?
In April 2006, a copyright infringement case, brought by authors Michael Baigent and Richard Leigh, claimed that Dan Brown stole ideas.
What was the outcome of the lawsuit brough by Michael Biagent and Richard Leigh claiming Dan Brown stole their ideas?
In April 2006 Dan Brown's publisher, Random House, won the copyright infringement case brought by authors Michael Baigent and Richard Leigh

Question: Who else sued him?
Self-contained rewrite: Who else sued Dan Brown besides Richard Leigh and Michael Baigent and Lewis Purdue?