Shaniesha Forbes disappeared back on January 4.
Her 20-year-old boyfriend, Christian Ferdinand, of Limestone, Maine, was arrested Thursday on a second-degree murder charge. He was taken into custody in Maine on Tuesday.
Forbes' family said they were unaware that the girl was involved in a relationship with anyone, let alone someone six years older than her.
Ferdinand was brought to the 63rd Precinct, where he reportedly made statements implicating himself. Evident was also found in his home, police said.
The medical examiner had determined that Forbes died of "homicidal asphyxiation." Police believe Ferdinand suffocated her after a fight over a possible pregnancy. He allegedly left the body in his home for several days before putting her in a suitcase, driving to Gerritsen Beach and setting it on fire.
Fobes' body was discovered just after 7 a.m. on January 6. It was reclassified as homicide on May 2.
Forbes had attended the Academy for Young Writers in Williamsburg. The Medical Examiner's report indicates that she was not pregnant.