The boyfriend of a 38-year-old woman found with her throat slit inside their Staten Island apartment this week has been arrested for her murder, cops said. 

Milton Bolton, 39, was arrested at 4 p.m. Wednesday, a day after his girlfriend Natasha Colon was discovered unconscious inside her apartment on Montgomery Avenue near Fort Place in St. George, according to police. 

Colon, who was found around 8:45 p.m. Tuesday, was rushed to Richmond University Medical Center, where she was pronounced dead. 

The motive for the deadly assault was not immediately known.