FLINT, Mich. -

With growing fears of an apparent serial killer on the loose in Flint, another stabbing has police investigating whether the latest stabbing is connected.

Police said a man Police said a man in his 40?s walked into a Flint area hospital Saturday morning with knife wounds and has been transferred to University of Michigan Hospital in Ann Arbor and is in critical condition

Authorities have released a sketch of a suspected serial killer who has stabbed five men to death and wounded another eight in Flint.

Investigators said that since May, the serial killer has been targeting vulnerable, small-framed African-American men. Two of the men he stabbed had special needs, police said.

"To me, he's a bully. He's picking on people smaller than him or somewhat vulnerable. He doesn't give a warning; he doesn?t rob them. He gives them no reason at all," said Flint police Lt. Tim Johnson during a news conference Thursday.

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Most of the stabbings have occurred late at night or early in the morning near major roadways in Flint and Flint Township, where authorities said it is easier for the killer to stalk people and flee quickly.

In many cases, the killer asks his victims for directions and then begins to repeatedly stab them, police said. Sometimes, the killer gives no warning at all, said officers.

In several occasions, he just got out of his vehicle, walked up and started stabbing his victims," said Johnson.

The most recent incident happened on Monday in the 2100 block of South Saginaw Street in Flint. Arnold Miller, 59, was stabbed to death.

Miller's slaying comes on the heels of the July 30 killing of 60-year-old Frank Kellybrew in Flint Township.

Kellybrew's body was found in front of the Italia Gardens Restaurant on Miller Road, police said.

Priscilla VanSickle told Local 4 that her 27-year-old nephew, who has special needs, was stabbed four times by the serial killer.

"He said he just started stabbing him and stabbing him. He's still in the hospital. He's not doing good at all," said VanSickle.

The serial killer is described as a white man in his late 20s to early 30s, about 5 feet 11 inches to 6 feet 2 inches tall with a heavy or muscular build.

He may have light-colored hair and usually wears a baseball cap during the attacks.

"He's a serial killer. He's crazy and needs to be locked up," said VanSickle.

Authorities are working with a forensic psychologist to determine whether the stabbings are racially motivated hate crimes.

Police have beefed up patrols in the area and are working on a sketch of the person suspected in the stabbings.

Michigan State Police will hold a press conference Monday in Flint to give an update to their investigation?s findings.

Anyone with information is asked to call the Flint Police Department or the Michigan State Police.