They insisted that no one had abused the baby. That there had to be a medical explanation.

"I know there is a disease that can cause these symptoms," Lisa told a doctor. "I'll need to call Cleveland Clinic to find out."

Geisinger staff considered that possibility. One test looked for a bleeding disorder called Von Willebrand disease. The results of that test were negative.

They also gave Lucas vitamin K - a common practice when coagulation disorders are suspected - though not right away.

Early on his second day in the hospital, Lucas suddenly went downhill. His lungs filled with blood, and his heart rate plummeted. Six hours later, after working to revive him, doctors gave him 1 milligram of the vitamin, and his clotting ability improved somewhat - suggesting he might have a deficiency.

But ultimately, the physicians concluded that only child abuse explained his symptoms. The law required them to report their suspicions to authorities, and they did.

The grim progression of the various doctors' opinions can be seen in their handwritten notations on the baby's hospital chart.

Aug. 27: "Possible shaken baby."

Aug. 29: "Probable shaken baby."

Aug. 30: "There can be no doubt whatsoever that this child is a victim of child abuse."

Three days later, Lucas died.

Awaiting blame

With Lucas gone, Lisa and Alejandro couldn't imagine going back to live in their house in State College.

Lisa took a leave from work, and the couple went to live with her parents in Hartstown, Crawford County, not far from Lucas' grave. On top of their grief, they knew an arrest could come any day.

But the District Attorney's Office in Centre County wasn't sure which parent to blame. Investigators took more than 11 months to make up their minds.

They reviewed the medical records, consulted with doctors, and spoke to people who knew the young couple. They asked Lisa and Alejandro if either thought the other was responsible for the baby's death. Neither did.

Finally, prosecutors took the case before a special state advisory board of medical and legal child-abuse experts, formed by the state attorney general in 1988 to help evaluate cases.

They asked: Did the child's injuries occur while he was in his father's care? Or could they have been inflicted earlier in the day, before his mother left for school?

Members of the board said that whatever had happened, it had occurred on the father's watch.