3rd teen suspect in killing of Barnard student Tessa Majors turns himself in

A third teenager surrendered Wednesday in the fatal stabbing of Barnard College first-year Tessa Majors, marking the arrest of the final teen suspected of involvement in her death.

Luchiano Lewis, 14, turned himself in Wednesday and is being charged as an adult. No additional arrests are expected in connection with the stabbing, sources familiar with the matter told ABC News.

Another 14-year-old boy, Rashaun Weaver, was charged on Saturday as an adult in the killing.

Weaver is charged with two counts of murder in the second degree -- including one count as intentional murder and one count as felony murder --and Lewis is charged with one count of murder in the second degree as felony murder. Both are charged with first- and second-degree robbery.

Weaver and Lewis both pleaded not guilty Wednesday.

Majors, 18, was stabbed to death on Dec. 11 in upper Manhattan's Morningside Park, just off the campus of Columbia University, as three teenagers tried to rob her.

When Majors tried to escape, Lewis allegedly stopped her, according to court documents and statements made on the record in court. The college student then broke free and staggered up the stairs where she collapsed, according to documents and statements in court.

Manhattan District Attorney Cy Vance said Majors' last words were "Help me! I'm being robbed."

Majors' father came to court as Weaver and Lewis were arraigned on Wednesday and remanded into custody.

A 13-year-old was previously charged with aiding the attack and is awaiting a March trial in family court.

DNA recovered from the Majors' nail matched Weaver's profile, according to court documents and court statements. Weaver was also heard on an audio recording describing hitting the victim with a knife, according to court documents and court statements.

Weaver is also charged with robbing a man at knife-point in Morningside Park days before Majors' death, according to court documents and court statements. Weaver allegedly logged into the man's phone hours after it was stolen, according to iCloud records.

Vance said in a statement Wednesday, "While a criminal process will never fully heal the unimaginable pain suffered by Tessa Majors’ family and friends, this indictment is a significant step forward on the path to justice."

"We are committed to holding these young people accountable, and equally committed to a fair process which safeguards their rights," Vance said. "This is how we will achieve true justice for Tessa and her loved ones."