Seven people were in custody yesterday on charges of second-degree murder and kidnapping in connection with the death of a Long Island real- estate broker whose body was found locked in a trunk in a Manhattan apartment Saturday.

The police said the victim, 60-year- old Thomas Vigliarolo of Jericho, had been missing since March 20, when he left his home to meet a client in New Jersey.

On April 2, his business partner received a ransom demand for $435,000, according to a police spokesman, Sgt. Diane Kubler.

An autopsy yesterday found that Mr. Vigliarolo had died of asphyxiation, said Dr. Beverly Leffers, a deputy chief medical examiner.