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Prison worker may have wanted escapees to kill her husband

District Attorney Andrew Wylie told NBC News Monday afternoon that he has "no comment" on a plot to kill Lyle Mitchell.

Investigators are looking into the possibility that Joyce Mitchell, the woman charged with helping two murderers escape a New York prison, may have wanted the inmates to kill her husband, a senior law enforcement official told NBC News Monday.

Mitchell, who worked at Clinton Correctional Facility as a tailor shop instructor,appeared in court briefly Monday after pleading not guilty Friday to charges of facilitating the escape of convicted killers David Sweat and Richard Matt.

The senior official said Monday that Joyce Mitchell may have asked the men to kill her husband, Lyle Mitchell, who also worked at the prison. But, when asked about that plot, Clinton County District Attorney Andrew Wylie simply said "no comment."

RELATED: Prison worker Joyce Mitchell pleads 'not guilty' at arraignment

Joyce Mitchell's attorney, Stephen Johnston, refused to comment on the case.

Meanwhile, her husband has retained his own lawyer. He is being questioned by police, but he has not been charged with a crime, his attorney told NBC News.

Wylie said Monday that he thinks the husband may have information about the part his wife played in the escape of the prisoners, who have been on the run for ten days.

"Lyle Mitchell has information. Joyce talked to him about her involvement during the last few days before she was arrested," Wylie said. He also noted that the prisoners likely had other people assist them in their complicated plan to break out of the maximum security portion of the prison.

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Joyce Mitchell was charmed by Matt to the point in which she "thought she was in love," officials have said. Sources familiar with the investigation said Monday that Mitchell was also investigated for an alleged sexual relationship with Sweat, but nothing substantive was found.

She planned to drive the getaway car for the escapees and run away with them on the morning they escaped before she got cold feet.

Her failure to show gives authorities hope that the two killers may not have gotten very far.

Wylie told NBC News that the prisoners had left post-it notes, markings and even some directions along their escape route in the prison.

More than 800 local, state and federal officials continued to search for Matt and Sweat for a tenth day Monday, and state police said they had covered 13 square miles in their search. 

Monica Alba contributed reporting. 

This article originally appeared on NBCNews.com.