WHITTIER — A 27-year-old woman accused of stabbing her boyfriend to death in late 2009, who prosecutors initially declined to file charges against, has been arrested on suspicion of murder, authorities said Sunday.

Investigators from the Los Angeles County Sheriff’s Homicide Bureau arrested Michelle Pacheco about 11 a.m. Thursday on suspicion of murder, according to sheriff’s officials and booking records. She is being held in lieu of $1 million bail.

The Los Angeles County District Attorney’s Office decided in late 2010 not to file charges against her for the Nov. 27, 2009, fatal stabbing of 29-year-old Sean Casillas, however the case remained under review.

Homicide detectives initially said it appeared that Casillas was stabbed during a fight with Pacheco at an apartment in the 14300 block of Mulberry Drive in an unincorporated county area near Whittier.

Casillas assaulted Pacheco with some sort of household object before the two wrestled over a steak knife and Casillas was ultimately stabbed in the chest, investigators have said.

The district attorney’s officials and the handling detectives could not be reached for comment Sunday for comment on the arrest.

Information on Pacheco’s initial court date was not available, however criminal defendants being held in custody are generally brought before a judge for arraignment with two working court days of arrest. Courts are closed Monday for the President’s Day holiday.