The sister of a construction worker who was stabbed and killed on Monday in what police are calling a spree of attacks in Manhattan is demanding justice for her brother — and urging city officials to do whatever it takes to keep the alleged perpetrator behind bars.

Random stabbings in New York City on Monday left three people dead. Police believe the attacks were all carried out by the same suspect, who faces murder charges.

Three unprovoked stabbings across Manhattan Monday morning left two men dead and one woman “fighting for her life,” according to the New York City Police Department. A man is in custody, police said.