Authorities have completed a search of the shattered cellphone of Philip D. Chism, the teenager accused of killing his math teacher at Danvers High School in October, but they are not divulging what they found. Carrie Kimball Monahan, spokeswoman for Essex District Attorney Jonathan W. Blodgett, confirmed that investigators filed a search warrant return with Essex Superior Court indicating that the search of the phone has been completed. But she said the return does not disclose what, if anything, was found. Chism was 14 when he allegedly killed Colleen Ritzer, 24, on Oct. 22, 2013.John Ellement can be reached at email@example.com. Martin Finucane can be reached at firstname.lastname@example.org.