The weapon that police say the accused killer of Fifth Avenue real-estate-agent-to the-stars Linda Stein told investigators she used in the homicide, a “yoga stick,” could raise questions in court.

“It’s hard to believe something that is used for yoga could be a murder weapon,” the lawyer for Stein’s two daughters, Edward Hayes, said. “In any case, it probably wouldn’t be heavy enough to do the job.”

Several yoga instructors in the city, including Stein’s personal yoga instructor, told The New York Sun they have never heard of a yoga stick. Investigators have yet to find the weapon used to bludgeon Stein to death in her Upper East Side apartment on October 30.

Leading up to her death, Stein, described by friends and family as a yoga enthusiast, practiced three times a week with a private yoga instructor, Patricia Smith.

Ms. Smith said that she has never heard of a yoga stick, let alone ever seen one inside of Stein’s Fifth Avenue apartment, where she gave Stein private yoga lessons.

When police obtained a confession to the homicide from Natavia Lowery, Stein’s personal assistant, Lowery had a difficult time describing the murder weapon, sources said. Police Commissioner Raymond Kelly said that Ms. Lowery told detectives the weapon was a “yoga stick” when he announced the arrest at a press conference on November 9.

It isn’t hard to imagine that a yoga stick could be confused with another type of exercise pole. Mr. Hayes called the weapon a pilates stick before Mr. Kelly made an official announcement about Ms. Lowery’s arrest.

However, Ms. Smith, who spent three days a week instructing Stein in yoga, said that Stein did not have any type of exercise stick or pole in her multimillion dollar apartment. She said Stein’s only pieces of exercise equipment were a few small dumbbells, which could hardly be confused with a stick or pole.

“The NYPD never said the yoga stick was the weapon. We said she told detectives it was. She may well have used something else,” deputy commissioner Paul Browne said in an e-mail.

Ms. Lowery was captured on videotape leaving Stein’s apartment with a shopping bag, which has not been recovered.

Other questions about Ms. Lowery’s confession have been raised in legal circles. Some defense lawyers have said the confession may not hold up in court.

Ms. Lowery’s family has been outspoken in claiming the confession was coerced. An aunt, Julia Carrow, told the Daily News that Ms. Lowery was not permitted by police to call her lawyer or her mother during an overnight interrogation at a police precinct on the Lower East Side of Manhattan.

Her defense has taken a similar stance, arguing that detectives took advantage of Ms. Lowery. Ms. Lowery’s lawyer, Gilbert Parris, who said he is not commenting on the case to the press, said at her arraignment that police stepped over legal boundaries when they questioned her in the hours before the confession without notifying him.

Still, police say they have Ms. Lowery’s confession, in which she admitted to bludgeoning Stein to death after the real estate agent blew marijuana smoke in her face, on videotape. After the killing, Ms. Lowery also made phone calls from Stein’s cell phone and removed money from her bank account at an automatic teller machine, police said.

As for the confession, the police have held a strong line. They argue that Ms. Lowery called detectives and voluntarily answered questions.

Ms. Lowery, who entered an innocent plea in Manhattan Criminal Court, is being held without bail.