Kelly said Sunday that authorities would be taking that match and other evidence to a grand jury, seeking a murder indictment against Littlejohn in the death of the graduate student last month. He didn't give a date for when the grand jury would get the case.
Littlejohn, in custody at a Rikers Island jail on a parole violation, has not been arrested in connection with St. Guillen's death.
Kelly said the plastic ties were used to bind St. Guillen's hands behind her back. He wouldn't comment on how blood got onto the restraints but said, "It is a very important piece of evidence for us."
Littlejohn, 41, was a bouncer at The Falls bar, where St. Guillen, 24, was last seen alive. A manager at the bar has told police he ordered Littlejohn to escort her out when she stayed sipping a drink past the 4 a.m. closing time; he recalled hearing the pair arguing before they disappeared through a side door.
Sometime during the next 17 hours, the student at John Jay College of Criminal Justice in Manhattan was raped, strangled and suffocated. Her naked and bound body was found in a remote section of Brooklyn on Feb. 25 with a sock stuffed in her mouth and her head wrapped with packaging tape.
Kelly said witnesses reported seeing Littlejohn and St. Guillen leaving the bar together and records put his cell phone near where her body was found.
A St. Guillen family spokesman had no immediate comment Sunday.
Littlejohn maintains his innocence. His attorney, Kevin O'Donnell, has said the parolee "feels like a scapegoat" and is "upset" because his picture has been published in newspapers across the country.
O'Donnell told ABC's "Good Morning America" Monday morning that he hadn't heard about the blood evidence until police held a press conference.
"I should be hearing about that evidence from the district attorney, not from the media," O'Donnell said. He also questioned why the evidence took two weeks to obtain. O'Donnell said he last spoke on Friday to Littlejohn, who "was hoping that the case would move forward."
Records show Littlejohn's first brush with the law came at age 17, when he robbed someone with a shotgun. Over the years, he was convicted on drug and gun charges using names like Darryl Banks, John Handsome and Jonathan Blaze — the name of a comic book character.
His aunt, Addie Harris, has defended him publicly in the St. Guillen case, arguing, "Many people have a record, but that doesn't mean he committed that type of crime."
"His past is his past. He can't escape that," O'Donnell said Monday.
Littlejohn shouldn't have been working at the bar St. Guillen visited because the job kept him out past his 9 p.m. parole curfew.