SALT LAKE CITY -

Authorities say a Utah mother's motive for killing six of her newborns was that she was addicted to methamphetamine and other drugs and didn't want to deal with the responsibility.

Pleasant Grove Police Capt. Mike Roberts told The Associated Press on Tuesday that 39-year-old Megan Huntsman was heavily into a meth addiction when she strangled or suffocated the infants from 1996 to 2006.

Roberts said she wasn't worried about the babies' health, but selfishly didn't want to care for them.

Authorities think a seventh baby found in her Pleasant Grove garage was stillborn.

Police had previously declined to discuss a motive in the case.

Utah authorities say DNA results confirm that the biological father of the babies is her estranged husband, Darren West, who lived with her during the decade the babies were killed before going to federal prison on drug charges from 2006 until January. He is not a suspect.

Roberts said results from the FBI also show that five of the babies were girls and two were boys. Roberts says all seven were full term.

Huntsman is in jail on $6 million bail, charged with six counts of first-degree murder.