Police officers in Flint, Michigan continued their search today for a man they believe is targeting and stabbing African American men.

The attacker, who witnesses have described as 6 feet tall and Caucasian, has stabbed at least 13 people (all black men), killing five of them.

The latest attack occurred early Monday morning on 49-year-old Arnold Minor.

Minor’s sister, Stephanie Ward, described her brother’s final day on earth to Detroit news outlets. She told of the relaxed Sunday they spent with family and how he decided to walk home from their mother’s house at about 1:30am.

At some point during his 10-mile journey, Arnold Minor encountered his killer. Police say that by the time they found his body, he had already bled to death.

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Some are describing the killer as a bully who seems to be preying on the vulnerable as all of the victims were smaller than their aggressor, attacked late at night and while by themselves.

While Michigan authorities have fielded reports of similar stabbings since mid-May, officials at the local NAACP branch complain that this murder is the first they’re hearing of the news.

Frances Gilcreast, local president of the civil rights organization, told reporters it’s alarming to learn about serial killings three months and 13 attacks after they began.