PHOENIX — A baby girl from Arizona has been found dead inside a donation box that was shipped to a warehouse in Texas, and Phoenix authorities said on Friday it will be extremely difficult to find out who placed the girl there.

The child was discovered at a warehouse in McAllen on Thursday as workers sorted through clothing shipped from the Phoenix area.

Investigators are waiting to hear from officials in Texas who are conducting an autopsy to determine whether the baby was born alive or stillborn, Phoenix police spokesman Sgt. Steve Martos said.

The child was apparently wrapped in a towel, placed in a cardboard box and left in one of nearly 400 donation boxes scattered in retail store parking lots across the region between Dec. 8 and Sunday.

The collected clothing and household items were sorted in Phoenix and the clothes sent to Texas on Monday, arriving two days later. The child was apparently not noticed by the crew working in Phoenix.

Homicide detectives assigned to the case will likely be able to narrow down where the child was left to a smaller number of donation boxes.

"But even if we narrow it down to a hundred it's still a challenge for us to determine which of the hundred," Martos said.

They also might be able to get some clues from the box.

But detectives will likely need a tip to solve the case, Martos said. He asked for anyone who knows of a pregnant woman who is no longer expecting but doesn't have a baby to contact authorities.