LONDON — A lawyer who accuses best-selling author Dan Brown of stealing ideas for his mega-selling conspiracy thriller "The Da Vinci Code" said Monday that the writer's evidence should be treated with "deep suspicion."

Making his closing submission at the end of a three-week trial, attorney Jonathan Rayner James also asked why Brown's wife, Blythe — who did a large chunk of the research for the novel — was not called as a witness in the copyright-infringement case.

Michael Baigent and Richard Leigh are suing "Da Vinci Code" publisher Random House, claiming Brown's book "appropriated the architecture" of their 1982 nonfiction book "The Holy Blood and the Holy Grail." Both books explore theories — dismissed by theologians — that Jesus married Mary Magdalene, the couple had a child and the bloodline survives.

In a written statement handed to the court Monday, Rayner James said Brown had copied from "The Holy Blood and the Holy Grail," but acknowledged he may have done so "unwittingly because of the research materials supplied by Blythe Brown."

"His evidence should be approached with deep suspicion," the lawyer said.

"He had almost no recollection of matters that related to timing. He would struggle to recall a year, was rarely able to recall a month. His general attitude in cross-examination was uncooperative," Rayner James said, referring to Brown's testimony during three days on the stand last week.

Brown, who flew from his home in New Hampshire to give evidence, was not in court Monday.

Rayner James said evidence from Blythe Brown would have been of "fundamental importance to this case." He claimed she would have been able to confirm the extent to which "The Da Vinci Code" relied on Baigent's and Leigh's work.

Dan Brown knew "little about what she did," Rayner James said.

"It remains the position that only she knows the extent of her involvement in the research and creation" of "The Da Vinci Code," he added.

Brown has acknowledged that he and Blythe read "The Holy Blood and the Holy Grail" while researching "The Da Vinci Code," but said they also used 38 other books and hundreds of documents, and that the British authors' book was not crucial to their work.

On Friday, Random House lawyer John Baldwin said Brown's work gathered a number of incidents and put them together in a unique way.

"The ideas are of too general a nature to be capable of copyright protection," Baldwin argued. "The claimants' claim relates to ideas at a high level of generality, which copyright does not protect."

If Baigent and Leigh succeed in securing an injunction to bar the use of their material, they could hold up the scheduled May 19 film release of "The Da Vinci Code," starring Tom Hanks and Audrey Tautou. Sony Pictures says it plans to release the film as scheduled.