Six of the rapes are thought to be related, with most of the cases coming from the city's northwest side, police said. One rape occurred in Hilliard.

Investigators dubbed the suspect as the 'Northwest Serial Rapist,' 10TV's Andy Hirsch reported.

SLIDESHOW: Surveillance Images Of Suspect

The first attack occurred on June 4, police said. The last four rapes occurred in October, with the most recent on Friday, Hirsh reported.

Investigators said five of the attacks occurred in apartment or condominium buildings. One rape occurred in a single-family home, Hirsch reported. The first four attacks occurred at about 5 a.m.

All of the alleged attacks occurred in the bedroom. Police said that the man forced his way into some of the homes while the doors were unlocked in other cases.

Police said it was unknown whether the man stalked his victims before the attacks, but they said it was possible that he was watching and learning routines.

"That's a concern that we have," said Columbus police Sgt. David Pelphrey, "that they're not spur of the moment, opportunistic type assaults. That there is some premeditation going into it; some stalking going into it."

The man used similar tactics in most of the assaults, leading police to investigate a link between them. Police said he had a weapon in all but one of the attacks and in some cases he covered the victim's head with a pillowcase.

Police said the man stole four of the victim's ATM or credit cards and used two of the stolen cards.

The man was described as 5 feet 5 inches to 5 feet 9 inches tall with a stocky build.

Police said it has been difficult for victims to provide investigators with a clear description of their attacker.

"We're dealing with very traumatized women; brief flash and concealed identity," Pelphrey said. "The totality of all those things equals a very vague description."

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