Terrifying doorbell footage has emerged of a man politely asking a woman step outside her home so that he can sexually assault and then murder her.

The horrified woman, Amanda Nowak, hid inside as the man asked her: "Are you sure? Are you positive? I just have a few questions for you.

Nowak claims she never responded to the man and called 911. Her husband, Chas Leek, remotely accessed Ring's intercom despite not being home and asked the man who he was and what he wanted.

The bearded man responded:

What I'm looking for is the girl in the house cause I'm going to rape her and kill her. Can you have her open the door?

He then added that he had a knife and a gun. The man eventually walked away from Nowak's home.

According to Nowak, who uploaded the footage online, the man is now in police custody.

Writing to Facebook, she wrote:

So this happened tonight... pretty scary! I was home alone. You'll hear my husband jump on The Ring after a bit, he wasn't here... I was hiding where this guy couldn't see me and I never said a word.. that whole beginning he's just talking to himself. Police were called, the lady from 911 stayed on the line until cop got here. File was reported and I showed him the video. Searching for him.. enough to arrest if they find him. Hubby is home now. Lock your doors friends!

The Las Vegas Police Department added that the investigation is ongoing, and that more information on the man's arrest will be released at some point.

Just hours after uploading the footage to Facebook, Nowak wrote: "UPDATE he is now in custody." She also thanked the communities response to the social media footage which led to the man's swift arrest.

Apparently the footage was enough for police to arrest the man, however at the time of writing his exact charges have not been made clear.

She wrote one more note, writing:

On a personal note, the power of community using social media is strong and this proves so! Thank you everyone! I'm just glad he's off the streets, and can't harm anyone else. I do not wish to further comment.

Stay safe out there people. It's terrifying to think what this poor woman had to go through.