Etan Patz, a 6-year-old boy from New York who went missing in 1979, was searched for Thursday in a basement of a SoHo building, according to CNN.com.
Authorities said they are looking for human remains or personal effects of Patz, who disappeared walking to school over three decades ago. "It's a very painstaking process," said NYPD Deputy Commissioner Paul Browne.
Patz was officially declared dead in 2001, when the family filed a civil suit against Jose Antonio Ramos. Ramos is serving a 20-year sentence for molesting a different boy and will be released this year.
May 25, which was the day Patz went missing, was declared National Missing Children's Day by Ronald Reagan.
Investigators are looking into other suspects outside of Ramos, according to CNN.com.
The search was suspended Sunday around 2 p.m. for operational reasons, according to the FBI.