NEW YORK (CNN/Money) - In closing arguments in the Martha Stewart trial Monday, the defense lawyer for Stewart's former broker and co-defendant Peter Bacanovic said the prosecution's case was a house of cards.

Repeating "it makes no sense" 23 times in the first hour of his closing argument, defense attorney Richard Strassberg tried to cast doubt on the credibility of the prosecution's star witness, Bacanovic's former assistant Doug Faneuil.

Strassberg described Faneuil as "a person with extreme motivation to shape the truth," and said he had twisted key facts in his testimony. During the trial, Faneuil testified that he told Stewart -- at Bacanovic's behest -- that ImClone founder Sam Waksal was trying to sell his shares that day.

Strassberg also suggested that Faneuil was so excited to know a celebrity that he could have tipped Stewart off without Bacanovic's instructions. "Doug Faneuil was starstruck in a scary, obsessive kind-of way," Strassberg told jurors in his summation.

Earlier Monday, Assistant U.S. Attorney Michael Schachter, summing up the government's case against Stewart and her broker, tried to paint a picture of intended deceit by the home decor expert and Bacanovic about her sale of ImClone Systems stock on Dec. 27, 2001.

Related Links • Opinion (U.S. v. Stewart and Bacanovic) • Superseding Indictment (U.S. v. Stewart and Bacanovic) • Court Ruling Dismissing 'Selective Prosecution' Defense • Stewart's Employment Agreement at Martha Stewart Living Omnimedia Inc.

"Martha Stewart and Peter Bacanovic had two options -- tell the truth or decline to be interviewed," Schachter said. "They chose an option the law does not allow -- to lie, conceal and cover up."

"She thought she would probably never get caught," Schachter told the jury. "They made serious mistakes and left behind a trail of evidence."

Schachter also tried to elevate the credibility of witnesses called by the prosecution, including Faneuil.

"Douglas Faneuil's demeanor on that witness stand showed you he tried his level best to tell the truth," Schachter argued. "Ask yourselves this, 'Why on earth would somebody make this up?' "

YOUR E-MAIL ALERTS Fraud Lawsuits Trials Corporate Scandals or Create your own Manage alerts | What is this?

Actor Brian Dennehy came to court Monday to show his support for Stewart, saying the two are "old, old, deep friends. I think that there are a lot of misconceptions about her."

On Tuesday, Bacanovic's defense is expected to speak for another hour, after which Stewart's attorney, Robert Morvillo, will give his closing argument. The prosecution will then have another chance to speak.

On Friday, U.S. District Judge Miriam Goldman Cedarbaum dismissed the securities fraud charge against the 62 year-old Stewart, saying that "the evidence and inferences the government presents are simply too weak to support a finding beyond a reasonable doubt of criminal intent." The four remaining charges she faces each carry a sentence of up to five years.

Securities fraud was the most serious charge against Stewart, carrying a penalty of up to 10 years in prison.

Stewart and Bacanovic still face obstruction of justice charges involving their statements to investigators after she sold nearly 4,000 shares of ImClone (IMCL: Research, Estimates) the day before bad news about the biotech firm's key drug started the stock plunging.

Bacanovic was broker to both Stewart and Waksal, who is serving a seven-year prison term after pleading guilty to securities fraud over his family's sale of the ImClone shares.

Stewart and Bacanovic told investigators that Stewart's sale was triggered by an arrangement to sell once the stock fell to $60.

Ironically, Erbitux, the ImClone drug that led to the insider trading scandal when its application was rejected, recently was approved to treat certain forms of cancer.

In the dropped charge, Stewart was accused of using her own statements that she was innocent as a ploy to mislead investors in her company, Martha Stewart Living Omnimedia (MSO: Research, Estimates). MSO stock started sinking last spring after questions surfaced about Stewart's sale of ImClone shares.

Neither Stewart nor Bacanovic testified at the trial -- the most closely watched case so far involving corporate executives accused of wrongdoing.

Defense lawyers met privately with Judge Cedarbaum Friday to discuss the instructions she will give to the jury when she gives them the case later this week. Those instructions themselves are a matter of contention between the two sides because of how they can shape the jury's debate.  

-- from CNNfn's Allan Chernoff and staff and wire reports