With the first funerals set to be held on Friday, Italy's Civil Protection department told NBC News the death toll had gone up to 267 overnight.
Adel Daoud, a U.S. citizen, was 18 when he was arrested in September 2012 on charges of plotting to bomb downtown Chicago.
The family's attorney, Vincent Paravato, says the ashes given back to the family in the box were not their mothers.
William Evertz's mom said her son has loved police officers since he was 2 years old and decided he wanted to have a "kindness day" to treat officers to a healthy lunch.
A truck laden with explosives blew up at a police checkpoint near the town of Cizre, in Sirnak province.