U.S. prosecutors worry a 99-year-old woman central to establishing the motive behind corruption-related charges against her granddaughter won't be available to testify at trial.

Prosecutors say Florence Puana needs to be deposed by April 26 because her health is deteriorating.

Puana is the grandmother of Katherine Kealoha, a former deputy prosecutor who is married to ex-Honolulu police chief Louis Kealoha. The Kealohas are accused of defrauding banks and relatives to fund their lavish lifestyle.

Prosecutors say Katherine Kealoha stole money from her grandmother and an uncle. Prosecutors say when they threatened to expose the fraud, Kealoha tried to have her grandmother declared incapacitated and framed her uncle for a mailbox theft.

The Kealohas pleaded not guilty.

A judge is giving the Kealohas until Monday to respond to the deposition motion.