TODAY | September 13, 2013
>>> back now at 8:43 with the court battle over a vast fortune. the heiress died leaving $300 million behind. large sums for her nurse, her attorney and her accountant but not her family raising a few questions. erica hill has the story.
>> clark and her legendary wealth is a story we have been following closely here for two years. now her will is challenged in court by distance family and a new account of the heiress spreading light on her final wishes. secretive and mysterious. for years she all but vanished.
>> she was cautious.
>> she was raised in one of the nation's wealthiest families with access to just about anything and anyone. yet she lived a largely reclusive life.
>> she talked on the phone a lot. she wrote a lot of letters.
>> why didn't she want to be around people?
>> she didn't do well with strangers or new people. i'm not sure we'll ever know what was the cause of her shyness.
>> reporter: in his book empty mansions, the nbc investigative reporter paints a detailed account of clark who died in 2011 . two weeks shy of her 105th birthday.
>> she had a fabulous collection of $50,000 french dolls. she was a painter, a collector of fine paintings and musical instruments .
>> reporter: clark 's properties were equally extravagant. 15,000 square feet on 5th avenue and an estate in santa barbara and this 22 room connecticut mansion which she never moved into. in fact, for the last 20 years of her life, clark didn't set foot in a single one of her homes. choosing, instead, to live in a new york city hospital room.
>> why did she end up there in the first place and why did she stay.
>> the event was she was sick. she had skin cancer .
>> reporter: once she recovered, she realized she was more comfortable there than at home and would spend the rest of her life, more than 7,000 nights in the hospital.
>> she insisted on staying. $400,000 a year will keep you in the hospital.
>> reporter: during that time, clark kept busy writing letters. some 20,000 pages were discovered after her death and struck up a close relationship with her private nurse. paul newell, the coarthur is her first cousin once removed. he reached out to her in 1994 .
>> she had a wonderful memory.
>> reporter: though they never met in person, he recorded their phone conversations.
>> hello paul .
>> hello, how are you?
>> okay. how is everything with you paul ?
>> she also had a collection of barbie dolls and was fond of the cartoon characters the smurfs.
>> she leaves behind a $300 million estate. she was generous with her fortune sending thousands to people she barely knew and giving away much more to those close to her like her aattorney, accountant and her nurse seen here in a 2012 deposition related to clark 's family 's contesting her will. perry received cash and lavish gifts from clark before she died and an additional $30 million in clark 's will. but as for her relatives, clark left them nothing.
>> she was very aware of who her family was. she just didn't want to leave them any money in the will.
>> reporter: a remarkable legacy with more questions than answers. and because of all the questions, her personal will is now being challenged in court by 19 relatives. some of whom want to see some of that pay out. at this point it is scheduled to go to court on tuesday. the book empty mansions is out now. a fascinating story.
>> a lot of twists and