Liberty Falling, by Nevada Barr (1999)

Liberty Falling, by Nevada Barr, was published in 1999.

Each of Barr's books takes place in some national park... on this occasion, the park is the Ellis Island National Monument - the island on which stands the Statue of Liberty, and the buildings that greeted legal immigrants during the 1920s.

Anna's sister, Molly, is deathly ill in a New York hospital, and Anna Pigeon has come to be with her, and in her spare time, to keep her sanity, she explores Liberty Island, and, as usual, comes across murder...and this time, a plot that could change America forever.

Here's the list of Nevada Barr books and the National Parks in which they take place:

Track of the Cat --Guadalupe Mountains National Park --1993
A Superior Death --Isle Royale National Park --1994
Ill Wind --Mesa Verde --National Park --1995
Firestorm --Lassen Volcanic National Park --1996
Endangered Species --Cumberland Island National Seashore --1997
Blind Descent --Carlsbad Caverns National Park --1998
Liberty Falling --Statue of Liberty National Monument --1999
Deep South --Natchez Trace Parkway --2000
Blood Lure -- Glacier National Park --2001
Hunting Season --Natchez Trace Parkway --February 2002
Flashback --Dry Tortugas National Park --February 2003
High Country --Yosemite National Park --February 2004
Hard Truth --Rocky Mountain National Park --March 2005
Winter Study --Isle Royale National Park --April 2008
Borderline --Big Bend National Park --April 2009
Burn New Orleans --Jazz National Historical Park August 2010