BERKELEY, CA - JULY 18: UC Berkeley Chancellor Nicholas Dirks speaks during a vigil in honor of Nicolas Leslie, a student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: People gather for a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: People comfort each other during a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: A man writes a message during a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: Written notes are seen on a paper during a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: Mourners during hold hands a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: People gather for a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)

BERKELEY, CA - JULY 18: Mourners write on a sheet of paper in Sproul Plaza during a vigil in honor of Nicolas Leslie, a UC Berkeley student killed in last week's truck attack in Nice, France, on July 18, 2016 at Sproul Plaza in Berkeley, California. Leslie, an environmental sciences major, was part of the university's study-abroad program in Nice during the attack. (Photo by Stephen Lam/Getty Images)