SACRAMENTO (CBS13) — An alleged serial rapist accused of preying on women for more than a year was arrested, but his father says they have the wrong man.

Robert Hill is accused of raping three women who were walking alone—once in North Highlands in April 2013 and twice this year in South Sacramento.

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His father, who wants his identity hidden, stands behind Hill, despite the accusations.

“He’s a good kid you know he’s a good kid, that’s all I’m going to say,” he said.

But Sacramento County Sheriff’s investigators paint a much different picture of the Sacramento man.

“I would say he is a serial rapist,” said Sgt. Lisa Bowman. “There was a female walking down the street he had come up from behind her placed some kind of choke hold on her and dragged her to the side where he forcibly sexually assaulted her.”

Detectives say Hill raped three women in their mid-20s in the last 15 months. The first attack happened in North Highlands on Melrose Drive in April 2013. The second was on Golf Club Court in South Sacramento, where investigators say he dragged the victim to an empty home.

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But it wasn’t until the most recent rape behind a building nearly three weeks ago on Massie Circle that investigators linked the case.

“Basically physical evidence at the scene connected the three cases,” Bowman said.

The last two rapes happened near where Hill used to live.

Still, his father says investigators have the wrong man.

“I believe the investigation is wrong,” he said. “He’s only 20 years old. I mean if this is true that’s a long time behind bars what’re you going to do?”

Investigators believe there are more victims who are too afraid to talk.

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“I know my son’s not capable of doing anything like that,” Hill’s father said. “It hurts real bad. I mean I can’t believe it. I couldn’t believe it when I heard it. All we gotta do is see what goes on in the investigation.”