Hofstra student Jessica Rebello, whose twin was slain in shooting, graduates in memory of her sister

The graduation cap worn Sunday by Jessica Rebello at Hofstra University's commencement served as a tribute to her slain twin sister Andrea Rebello, who was accidentally shot and killed by a Nassau police officer during a hostage standoff.

The black mortarboard was emblazoned with Andrea's initials -- AR in purple, glittery letters. White wings stemmed from the letters, each of which was festooned with a heart. The "A" was topped with a gold halo. Also written in white letters was Beta Sigma Phi, the sorority to which both sisters belonged.

Jessica Rebello, who like her twin sister also majored in public relations at the Hempstead college, received a bachelor of arts degree from Hofstra's Lawrence Herbert School of Communication -- a year and a day after her sister's death.

In a post on her Instagram page hours before the graduation ceremony, Jessica Rebello, in a white dress, modeled her cap and wrote: "I don't know how I did it . . . but I did it . . . for you." She said she loved and missed her sister and ended the message with -- "until we meet again Twinnie . . ."

Hofstra president Stuart Rabinowitz greeted Rebello in a private conversation as she took to the stage to receive her diploma and kissed her cheek. Her faculty adviser, Jeffrey Morosoff, a professor of public relations, hugged her.

A Hofstra University spokeswoman said the family did not wish to comment.

Andrea Rebello, a then 21-year-old junior from Tarrytown, was killed May 17, 2013, after an armed intruder, Dalton Smith, entered the off-campus Uniondale apartment she shared with her sister and two others demanding money.

Officer Nikolas Budimlic entered the home and fired eight rounds after confronting Smith, 30, of Hempstead, as he held Rebello in a chokehold, police said. Bullets from his gun killed both Smith and Rebello, police have said.

The Rebello family filed a wrongful-death lawsuit on Friday against Nassau County and its police force, alleging the officer who fired the fatal shot "carelessly discharged his pistol," and authorities "recklessly and unnecessarily" endangered her.

On her LinkedIn page, Jessica Rebello said she is the founder of the Andrea Rebello Fund. Its goal, according to the fund's webpage, is "to raise awareness in gun control as well as to create a scholarship fund in her name and most importantly, to forever celebrate my twin sisters life."