Authorities said the victim's daughter, who was on the cast of "Saturday Night Live," had been told of her father's death.
Police say Fagan and the victim were roommates.
Police said Fagan had been arrested Saturday night on a charge of driving under the influence, and shortly after he posted bail on Sunday a friend of the roommates told police their door was locked, the house appeared to be in disarray and Oteri wasn't answering the door.
Emergency medical technicians found Oteri dead in the house.
It appears that Oteri he died from a "significant laceration" to his wrist caused by Fagan's knife, police spokesman Don Aaron said.
Police said detectives found Fagan while he was still with his bail bondsman.
Jail officials say they don't have a record of an attorney for Fagan.
Fagan is listed as co-writer on hits by singer John Michael Montgomery, including "Sold (the Grundy County Auction Incident)," "Be My Baby Tonight," and "I Miss You a Little."
Fagan told police his songs have been recorded by several country artists.
Cheri Oteri grew up in Upper Darby, Pa. and graduated from Archbishop Prendergast High School before moving to Los Angeles when she was 25.
