The man police believe pulled an 8-inch knife on a 19-year-old woman at public library in Glastonbury turned himself in Wednesday morning.
Authorities say Lucky Rice threatened the girl with a knife and took her laptop computer, money and other items on Aug. 12 as she sat in a study room at the Welles Turner Library.
Police responded but there was no sign of the man.
A state judge has signed an arrest warrant charging Rice with robbery and larceny.
Rice couldn't be reached for comment, and it's not clear if he has a lawyer.
The incident prompted increased patrols around the library and staff members have increased their presence in secluded areas and are also considering adding security cameras at both entrances.