. >>> ALL RIGHT.

. >>> ALL RIGHT. WE'RE BACK NOW WITH

>>> ALL RIGHT. WE'RE BACK NOW WITH THE VIOLENT CRIME

WE'RE BACK NOW WITH THE VIOLENT CRIME CAPTURED ON A DOORBELL

THE VIOLENT CRIME CAPTURED ON A DOORBELL CAMERA AND HOW IT

CAPTURED ON A DOORBELL CAMERA AND HOW IT HELPED POLICE TRACK

CAMERA AND HOW IT HELPED POLICE TRACK DOWNA

HELPED POLICE TRACK DOWNA ALLEGEDLY KIDNAPPED

DOWNA ALLEGEDLY KIDNAPPED AND KILLED A WOMAN.

ALLEGEDLY KIDNAPPED AND KILLED A WOMAN. THE WARNING, THE VIDEO

AND KILLED A WOMAN. THE WARNING, THE VIDEO IS DISTURBING.

THE WARNING, THE VIDEO IS DISTURBING. >> Reporter: LAS VEGAS

IS DISTURBING. >> Reporter: LAS VEGAS POLICE RELEASED THE

>> Reporter: LAS VEGAS POLICE RELEASED THE GRAPHIC DOORBELL VIDEO

POLICE RELEASED THE GRAPHIC DOORBELL VIDEO HOPING TO CAPTURE THE

GRAPHIC DOORBELL VIDEO HOPING TO CAPTURE THE SUSPECT AND TO

HOPING TO CAPTURE THE SUSPECT AND TO IDENTIFY THE VICTIM.

SUSPECT AND TO IDENTIFY THE VICTIM. WHO WAS BEATEN AS SHE

IDENTIFY THE VICTIM. WHO WAS BEATEN AS SHE RAN FOR HELP AFTER

WHO WAS BEATEN AS SHE RAN FOR HELP AFTER POUNDING ON A STRANGER

RAN FOR HELP AFTER POUNDING ON A STRANGER STRANGER'S DOOR.

POUNDING ON A STRANGER STRANGER'S DOOR. TONIGHT HOURS AFTER

STRANGER'S DOOR. TONIGHT HOURS AFTER RELEASING VIDEO,

TONIGHT HOURS AFTER RELEASING VIDEO, OFFICERS ARRESTED

RELEASING VIDEO, OFFICERS ARRESTED DARNELL ROGERS AND

OFFICERS ARRESTED DARNELL ROGERS AND FOUND THE WOMAN WHO

DARNELL ROGERS AND FOUND THE WOMAN WHO WAS ATTACKED AND IS

FOUND THE WOMAN WHO WAS ATTACKED AND IS NOW RECOVERING.

WAS ATTACKED AND IS NOW RECOVERING. >> THESE SURVEILLANCE

NOW RECOVERING. >> THESE SURVEILLANCE SYSTEMS ARE SO HELPFUL

>> THESE SURVEILLANCE SYSTEMS ARE SO HELPFUL FOR US.

SYSTEMS ARE SO HELPFUL FOR US. >> Reporter: WITH

FOR US. >> Reporter: WITH DOORBELL CAMERAS MORE

>> Reporter: WITH DOORBELL CAMERAS MORE PREVALENT THAN EVER,

DOORBELL CAMERAS MORE PREVALENT THAN EVER, THEY ARE BEING WIDELY

PREVALENT THAN EVER, THEY ARE BEING WIDELY USED BY DETECTIVES TO

THEY ARE BEING WIDELY USED BY DETECTIVES TO HELP SOLVE CRIMES.

USED BY DETECTIVES TO HELP SOLVE CRIMES. >> NO!

HELP SOLVE CRIMES. >> NO! >> Reporter: OUTSIDE

>> NO! >> Reporter: OUTSIDE LOS ANGELES, POLICE

>> Reporter: OUTSIDE LOS ANGELES, POLICE ARRESTED ROBERT MANDEZ

LOS ANGELES, POLICE ARRESTED ROBERT MANDEZ AFTER A SECURITY

ARRESTED ROBERT MANDEZ AFTER A SECURITY SYSTEM CAPTURED HIM

AFTER A SECURITY SYSTEM CAPTURED HIM ASSAULTING HIS

SYSTEM CAPTURED HIM ASSAULTING HIS EX-GIRLFRIEND.

ASSAULTING HIS EX-GIRLFRIEND. DAYS EARLIER AFTER A

EX-GIRLFRIEND. DAYS EARLIER AFTER A REALTOR WAS ATTACKED

DAYS EARLIER AFTER A REALTOR WAS ATTACKED DURING AN OPEN HOUSE,

REALTOR WAS ATTACKED DURING AN OPEN HOUSE, THE SUSPECT WAS

DURING AN OPEN HOUSE, THE SUSPECT WAS ARRESTED AFTER OTHER

THE SUSPECT WAS ARRESTED AFTER OTHER AGENTS SAW THE VIDEO

ARRESTED AFTER OTHER AGENTS SAW THE VIDEO AND RECOGNIZED THE

AGENTS SAW THE VIDEO AND RECOGNIZED THE MAN.

AND RECOGNIZED THE MAN. >> PUT THAT DOWN.

MAN. >> PUT THAT DOWN. >> Reporter: FROM

>> PUT THAT DOWN. >> Reporter: FROM CAPTURING PORCH

>> Reporter: FROM CAPTURING PORCH PIRATES TO VIOLENT

CAPTURING PORCH PIRATES TO VIOLENT CRIMES, TONIGHT, THESE

PIRATES TO VIOLENT CRIMES, TONIGHT, THESE CAMERAS ARE HELPING

CRIMES, TONIGHT, THESE CAMERAS ARE HELPING POLICE BY WATCHING