Why Did a Popular, Smart, Athletic College Freshman Kill Herself?
01/23/2015 AT 06:40 AM EST
In August 2013 she began her freshman year at the University of Pennsylvania in Philadelphia, eager to run track.
"Penn just may be the greatest place on earth," the Allendale, New Jersey, teen Tweeted on Aug. 25.
But by December she was seeking help for depression at the student health center. Then, on Jan. 17, 2014, Holleran, 19, killed herself by jumping from a parking garage.
Still deep in grief and searching for answers a year later, her loved ones hope sharing her story might save another student struggling far from home.
"Depression can affect anyone, no matter how successful or well loved," says her dad, Jim Holleran, 53.
With PEOPLE writer Nicki Egan, those closest to Madison – along with others who encountered her in her final days – try to retrace what went wrong.