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PHILADELPHIA (CBS) — The major arrest of a city worker led to some troubling revelations. Authorities say he is the man suspected of sexually assaulting and terrorizing women in South Philadelphia.

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Not only is 37-year-old Safien Williams a city employee, officials never performed a background check on him.

The air of cautious relief can be felt in South Philly.

“I feel much more comfortable,” one woman said.

“Innocent until proven guilty, but it certainly brings some peace of mind to the neighborhood that somebody of interest is in custody,” one man said.

Williams was taken into custody as a person of interest Monday, before being arrested Tuesday.

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“An arrest was made of a very violent predator who essentially terrorized an entire neighborhood,” Philadelphia Police Commissioner Richard Ross said.

Turns out, Williams is a city worker who was hired last July as a semi-skilled laborer for the Streets Department, according to a city spokesperson.

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His arrest record shows previous charges for assault and theft, but nothing sexual in nature.

Eyewitness News has learned the Streets Department does not require background checks for his position.

“Absolutely, yes. Everyone who is being hired for any kind of job should have a background check, for sure,” neighbor Sloane Murray said.

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“It’s so simple to do a background check,” said another woman.

Investigators have tied Williams to at least four sexual assaults, all in South Philadelphia, between May 20, 2018 and last Friday.

Credit: CBS3

Police say Williams used a bicycle to track down women, always between midnight and 6:30 a.m. in the morning, before police say he sexually assaulted them at knifepoint.

But with this arrest, it’s a return to normalcy for many.

“I don’t feel like I have to be looking over my shoulder all the time as much as I used to, so it’s great,” another woman said.

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Investigators say Williams may be connected to other sexual assaults dating back to 2017.