PLEASANT GROVE, Utah — Megan Huntsman was clear about what she did with six of her newborn babies.

Huntsman, 39, told police she either strangled or suffocated them immediately after they were born. She wrapped their bodies in a towel or a shirt, put them in plastic bags and then packed them inside boxes in the garage of her home south of Salt Lake City.

What’s not clear is why. A day after her arrest on charges of killing her six babies, investigators and her neighbors puzzled over the grisly discovery, including how she could have concealed a half-dozen pregnancies over a 10-year period.

“How can you have a baby and not have evidence and other people know?” asked neighbor SanDee Wall. “You can’t plan when a baby is going to come. Just the thought of somebody putting a baby into a box is a heartbreaker.”

Huntsman, who was arrested Sunday on six counts of murder, was ordered held on $6 million bail — $1 million for each baby. The remains of a seventh baby police found appears to have been stillborn, authorities said.