A registered nurse was savagely murdered by her boyfriend in Illinois … and the suspect recorded more than 7 hours of her being tortured, sexually assaulted and strangled, according to police.

The grisly recording was discovered on April 30 when police took Kevin Motykie into custody in the garage of the suburban Chicago home he shared with former longtime partner, Katherine Torbick, who was found dead at the scene.

Schaumburg Police detectives reportedly discovered an audio recording device in Motykie’s pocket as he was being arrested — which allegedly holds evidence of the murder.

Investigators got a search warrant and examined the full contents of the device, allegedly depicting more than 7 hours of shocking criminal activity between 2 AM and 9:24 AM on April 30, WBBM-TV reports.

In the audio, Motykie allegedly handcuffed and battered Torbick before sexually assaulting her, strangling her, and ultimately killing her. During the brutal encounter, prosecutors say Torbick was begging for Motykie to get off her, and pleading with him not to cuff her.

Motykie has been charged with first-degree murder and sexual assault.

Prosecutors say Motykie launched the vicious attack after accusing Torbick of cheating on him. At Friday’s detention hearing, prosecutors described Torbick as a mother who was also a gastroenterology nurse employed by a medical spa. She had previously gone to police in fear of Motykie, and had filed a felony complaint against him in March.