Honolulu police arrested a 26-year-old man after he allegedly threatened and robbed his ex-girlfriend in Waimanalo.

Police said the suspect held the victim, 24, against her will in her vehicle at about 4 p.m. Sunday. He allegedly threatened her while brandishing a box cutter or knife and demanded money.

At some point, the suspect dropped her off at her house and fled in her vehicle.

Police were called.

At about 7:35 a.m. the next day, responding officers found the suspect sleeping in the vehicle on Lohe Place at Whitmore Village in Wahiawa and observed an open container of alcohol in his possession.

After officers placed him under arrest, police said an officer found a glass pipe that contained drugs in his possession during a pat-down search.

Police arrested him on suspicion of kidnapping, first-degree robbery, auto theft, promoting a dangerous drug in the third degree, possession of intoxicating liquor while operating a motor vehicle, operating a vehicle after suspension or revocation of his license and two counts of criminal contempt of court.