SIOUX CITY -- A federal judge has vacated the death sentence of an Iowa woman convicted of helping her boyfriend kill five people near Mason City, Iowa.

Angela Johnson, 48, of Forest City, Iowa, was convicted in U.S. District Court in Sioux City in 2005 of helping Dustin Honken kill five people -- including two little girls -- in 1993 to cover up evidence of drug crimes. The same jury then recommended Johnson be sentenced to death for four of the slayings and receive life in prison for the fifth death.

On Thursday, U.S. District Judge Mark W. Bennett filed a 448-page ruling in which he found four instances of ineffective legal counsel during the penalty phase of Johnson's trial that may have adversely affected the jury's sentencing recommendation. Bennett's ruling does not affect Johnson's guilty verdicts. She remains incarcerated in Fort Worth, Texas.

U.S. Department of Justice officials have 60 days to appeal Bennett's ruling, decide not to seek the death penalty and have Bennett sentence Johnson to life in prison without parole or continue to seek the death penalty and request a new penalty phase of the trial before a jury.

Assistant U.S. Attorney C.J. Williams, who prosecuted both Johnson and Honken, said Friday the decision on how to proceed in the case will be made by Justice officials in Washington, D.C. He declined to comment on Bennett's ruling.

Honken, 44, of Britt, Iowa, was convicted in a separate trial and also sentenced to death.

Johnson had filed 64 claims for postconviction relief of her death sentence. Evidence was heard in 2011 in Sioux City during four phases of hearings that included 19 days of testimony from 58 witnesses and thousands of pages of legal briefs.

Bennett found four instances in which decisions made by Johnson's trial attorneys were prejudicial, "that is, there is a reasonable probability that, had her trial counsel not performed deficiently, the outcome of Johnson's mitigation phase would have been different," Bennett wrote.

Those four claims involved errors regarding mental health evidence.

Bennett, who presided over the trials of both Honken and Johnson, acknowledged in his ruling that his decision would disappoint the murder victims' families and said he did not take his decision lightly.

"My heart does go out to them," Bennett wrote on the second-to-last page of the lengthy decision. "Nevertheless, I believe that I have done my duty, in light of what is required by the Constitution -- the foundational document of our Nation's enduring freedoms, including the right not to be put to death when trial counsel's performance was so grossly constitutionally inadequate."