An Arizona woman charged with drowning her 2-year-old twin sons and trying to kill a third boy has pleaded not guilty.

Maricopa County Superior Court officials say 22-year-old Mireya Alejandra Lopez, of the Phoenix suburb of Avondale, entered her plea Tuesday to two counts of first-degree murder and one charge of attempted murder.

Avondale police say Lopez told investigators she killed her sons because nobody loved them or her and she didn't want them to have difficult lives.

She's also accused of trying to drown a 3-year-old identified by police as her stepbrother.

Her court-appointed lawyer did not immediately respond to a request for comment.