Nebraska Medical Center officials are investigating after a 23-month-old patient died following an overdose of a blood thinner.

Spokeswoman Andrea McMaster says too much Heparin contributed to the Wednesday evening death of Almariah Duque, but may not have been the sole cause.

She says the Dallas, Texas, girl was being treated for an infection, but didn't know how long she'd been hospitalized. The girl received a multiple organ transplant at the Omaha hospital in December.

Heparin is used in heart surgery, kidney dialysis and a variety of other medical procedures. McMaster says she doesn't know why the girl was given Heparin.