Nicole Elizabeth Ebaugh, 29, of New Freedom, Pennsylvania, has been missing
Her family reported her missing on Saturday after she went to a state park
Ebaugh s car found in parking lot near Heritage Rail Trail County Park in York
On Sunday and Monday, some 150 volunteers and officials combed the area
They used horseback, helicopter, and dogs while searching half-mile radius
On Tuesday, state police said that no search party would be sent to the field
Investigators said search would resume if there are new developments in probe
Ebaugh is white, 5ft4in tall with thin build and light-brown shoulder-length hair