Family of the ex-wife of troubled New York real estate heir Robert Durst have asked a judge to declare her legally dead 34 years after she was last seen.

In affidavits filed in Manhattan Surrogate's Court this week, Kathleen Durst's sisters and mother ask a judge to issue a death certificate.

They need a judge's declaration to pursue a wrongful death lawsuit against Robert Durst.

The family believes the 72-year-old millionaire killed Kathleen Durst in 1982. He hasn't been charged in connection with her disappearance.

Los Angeles prosecutors allege Durst killed a friend in 2000 to keep her from talking to authorities about Kathleen.

Attorney Richard DeGuerin (duh-GEHR'-uhn) says Durst is not responsible for the death or the disappearance.

He pleaded guilty last month to a weapons charge in Louisiana.