A Manhattan personal assistant has told investigators that she fatally bludgeoned her boss, the well-connected real estate agent Linda Stein, in the woman’s opulent Fifth Avenue apartment because Ms. Stein swore at her, waved a stick at her and blew marijuana smoke into her face, the police said today.

The assistant, Natavia Lowery, 26, of Brooklyn, was arrested this morning. At an afternoon news conference, Police Commissioner Raymond W. Kelly said Ms. Lowery had told the police that she struck Ms. Stein six or seven times on Oct. 30 with a four-pound exercise stick.

Mr. Kelly said that in Ms. Lowery’s account, Ms. Stein had used “profanity and derogatory language” and refused to stop blowing smoke at her even though the smoke was making her sick. Ms. Lowery had worked for Ms. Stein for about four months, but said Ms. Stein had not verbally abused her until the day of the killing.

Ms. Lowery, who was held at the Seventh Precinct on the Lower East Side, was to be charged by the Manhattan district attorney’s office this evening.