The lawyer for the two men who say Dan Brown stole from their book for his novel "The Da Vinci Code" faced sharp and relentless questioning from the judge in the case during closing arguments in the High Court here on Monday.

The judge, Peter Jones, will not issue a decision for several weeks, and it is impossible to know how he will rule. But his tough questions appeared to reflect skepticism, even exasperation, toward some of the arguments put forward by the lawyer for the plaintiffs, Michael Baigent and Richard Leigh, two of the three authors of "The Holy Blood and the Holy Grail." (The book's other author, Henry Lincoln, is not taking part in the lawsuit.) They claim that Mr. Brown lifted the central "architecture" for his megaselling "Da Vinci Code" from their nonfiction book, published in 1982.

For instance, when the lawyer, Jonathan Rayner James, argued that Mr. Brown had "been hiding the truth" about when he and his wife, Blythe Brown, who does much of his research, had first consulted "The Holy Blood and the Holy Grail," Justice Jones stopped him short. If that were true, the judge asked, why had Mr. Brown left out "The Holy Blood and the Holy Grail" from the bibliography he submitted to the publisher, along with a synopsis of "The Da Vinci Code" in January 2001 — only to include a pointed reference to the book in the finished novel a year later?