By LEE BOWMAN

It starts with a phone call about a small life suddenly ended. A baby found lifeless, unable to be revived.

Almost all of the more than 4,000 sudden and unexpected infant deaths in this country each year prompt a detailed investigation into the circumstances and an autopsy.

Rachel and Jesse Yerbich: Rachel Yerbich, 25, and her husband Jesse Yerbich, 29, of Havre, Mont., hold a homemade quilt and teddy bear made out of their 4 1/2-month-old son's, Benjamin Allen Yerbich, clothes. The infant died of Sudden Infant Death Syndrome on Sept. 26, 2006.Details vary from jurisdiction to jurisdiction, but most of the time, the investigation begins at a hospital. Emergency medical workers usually try to resuscitate infants who aren't breathing, and rarely concede the fight before getting a baby to an emergency department.

But whether an infant is pronounced dead at a hospital, the home or some other setting, the need for police or investigators from the local coroner or medical examiner to quickly begin gathering facts inevitably intrudes on grieving families.

"The shock hit me so hard at the hospital. After they pronounced her, they let me into the room to see her, but they'd left the breathing tube in her throat. It just seemed so cold to me," said April Poole of Huntsburg, Ohio, of the moments after she lost her daughter, Sommer, in 2005.

Rachel Yerbich, whose son, Benjamin Allen, died suddenly in Granite Falls, Minn., last September, recalls spending much of the night holding her son in a family room of the ER. "They unhooked him from all the machines and let me carry him in there and say goodbye, let my family gather with me to say goodbye."

But other parents report not being able to hold, or even touch, their dead infant at a death scene, even at the hospital.

"There are some medical examiners who are totally against allowing contact
with the infant's body before the investigation," said Dr. Deborah Kay, assistant chief medical examiner for the Virginia Office of the Chief Medical Examiner's Central Region in Richmond.

Kay said the Virginia medical examiner is issuing new guidelines for physicians and hospitals caring for infants and children who die suddenly and unexpectedly and whose deaths are subject to investigation.

"We wanted to have some consistency in what's being done around the state, while trying to be compassionate to the families," Kay explained. The instructions call for the body to be left unchanged from the time of death, including leaving in place any therapy items and preserving all clothing and bedding that came to the hospital.

Dr. Ronald O'Halloran: Dr. Ron O'Halloran is the chief medical examiner for Ventura County, Calif.Viewing is allowed under the supervision of hospital staff, and parents may hold the infant in cases where there is no known or suspected child abuse or neglect, as long as this is done in the presence of law enforcement officials.

Typically, investigators will attempt to interview parents and others familiar with the care of the infant at the hospital, separately, even though many families want to cling together at such a time.

"It was awful, not having any support when the investigator is asking all these questions, and you've just lost a baby, and you begin wondering what you did wrong," Yerbich said. "I know some people kill their babies, but you wish there was some other way for them to get the information."

"Although painful for the family, a detailed investigation may shed light on the true cause of death," wrote FBI Special Agent Ernst Weyand in a 2004 article on sudden infant death investigations published in the FBI Law Enforcement Bulletin. "Crucial evidence will become lost or destroyed if the investigation does not begin immediately."

The FBI agent, who became familiar with infant death investigations while heading the bureau's division responsible for American Indian reservations, reminded colleagues that Sudden Infant Death Syndrome is diagnosed far more often than abuse or neglect, "but without a complete investigation, the circumstances of a baby's death will remain a mystery."

Weyand says that, ideally, investigators should be dispatched both to the hospital and to where the baby was first found, allowing them to see the death scene as it was as much as possible, before well-meaning friends and family "straighten up."

Investigators want to see where the baby was found, often asking a parent or other person who found the child to demonstrate the position using a life-sized doll. They'll note the type and arrangement of bedding, and will take sheets and blankets and pillows for analysis.

A long checklist of questions has to be run through both at the hospital and home: the health history of the child and relatives, including the mother's prenatal health and care, any recent illness among other family members, whether anyone in the house smokes, how the house is heated and ventilated, what had been the routine for the baby, what went on in the hours before he or she died.

"The treatment of parents is still a work in progress. They may be puzzled by getting asked those types of questions, about things they may never have imagined happening. It's a most emotionally disturbing thing, but it is the most important thing, too," Kay said.

Dr. Karen Chancellor: Dr. Karen Chancellor, the medical examiner for Shelby County, Tenn., examines an X-ray of an infant who stopped breathing while sleeping in her home recently. Infant deaths like this one are investigated and counted in a variety of ways across America. "The more family and medical background we have prior to the autopsy, the better, because then the medical examiner has a pretty good idea of what's occurred."

As soon as possible after a baby is pronounced dead, investigators photograph the body, noting how blood has pooled (livor mortis) as an indicator of position and length of time from death, as well as any bruises or other signs of trauma to the body. It sometimes requires an expert eye to distinguish natural lividity from child abuse.

Getting accurate information about the condition of the baby's body is the main reason medical examiners are anxious about letting parents touch or hold the infant. The marks of grief-stricken embrace may be hard to distinguish from injuries inflicted when the baby was alive.

Pressure marks may be seen on the baby's head or body. These typically are left by a toy or bedding that the child was lying against. There may be a frothy white or blood-tinged discharge around the baby's nose or mouth, and found on clothes or bedding. This is a result of the death, not a cause.

When the infant's body arrives at the morgue, it is weighed and labeled and may be further photographed for identification. The protocol in Virginia and many other jurisdictions calls for a full-body X-ray to be done, which allows pathologists to be aware of congenital abnormalities, fractures or other injuries.

On the autopsy table, the baby is laid out for an external exam. The autopsy team notes details a mother would know by heart -- the color and length of hair, the color and condition of the eyes, the fingernails, the arms and legs, and the tone and color of the skin -- as well as for the abnormal, signs of bruising, of illness or violence.

Anything that the pathologist finds, or doesn't find, is noted.

Next, fluid samples are taken -- a nose swab for viruses, blood and spinal fluid drawn by syringe. A basic list of drugs is checked for -- aspirin, acetaminophen, opiates, cocaine and alcohol, as well as for any specific substances that might have come up in interviews with the parents or the scene investigation -- from prescription drugs to household cleaners.

Only after the external samples are taken is the body washed.

Then, the internal examination begins, the surgical opening of the chest, the skull. Each vital organ is examined, more photos taken, toxicology and other tests done.

Typically, an autopsy report from a sudden infant death may note congestion and fluid in the lungs, small burst blood vessels on the surface of the lungs and other organs in the chest cavity, perhaps some inflammation in the lungs and airway, but no evidence of any trauma, any malformation or disease that could have led to death.

"Medically, there's really nothing specific that separates an infant who accidentally suffocated and one that died from SIDS," Kay said. "The determination has to come from the scene investigation, the circumstances in which the baby was found."

Absent the discovery of anything unusual, or some complicated medical history, the procedure takes three or four hours in the hands of a skilled autopsy team.

But while she has a professional interest in researching infant deaths, neither Kay nor anyone else on the ME's staff is routinely called to take part in infant autopsies. "We do try to rotate procedures involving children," Kay said. "There is some emotional toll from working on an infant that you don't usually have with older people, and you need to have some time in between them if possible."

Unless the autopsy or investigation found evidence suggesting criminal behavior, the remains are then released to a funeral director to be prepared for burial or cremation. In most cases, no more than 24 to 48 hours pass from an infant's death to the release of the body.

But in some jurisdictions, it can take months to resolve an infant death investigation and issue a death certificate.

"It took us about seven weeks to receive a report from the coroner, although they had called me a couple of times with some information before that," said Signe Newcomb of Monroe County, Mich., whose 10-week-old son, Gaven, stopped breathing at a caregiver's home in March 2002.

In some areas, coroners and medical examiners call or meet in person with parents to keep them apprised of what they've found, or not found, and perhaps tell them what they believe caused or contributed to the child's death. Many jurisdictions try to get preliminary autopsy results to parents within 24 to 48 hours of a death.

Others only reach out to families after they have all the test results back and reviewed, often by a team of pathologists, and some even refuse to discuss their findings.

"I sat in the coroner's office all day. He refused to see me. After I sat in his office eight hours, I was told I'd have to find other means to answer my question," said Meta Dupuis of Glen Falls, N.Y., who lost her son, Michael, to SIDS in March 1997, at 6 months of age.

"I didn't get a death certificate back for seven months. I was lucky. There was another woman in our support group who didn't get anything back for more than a year."

A little more than half the time in recent years nationwide, the investigation simply rules out any medical cause of death, and the cause is attributed to SIDS. In a growing number of cases, though, investigators find some confounding factor that doesn't match the classic SIDS diagnosis of exclusion.

"Many law enforcement agents find the SUID (sudden unexplained infant death) investigation enigmatic," said FBI agent Weyand. "Instead of looking for possible wrongdoing, they often must focus their efforts on establishing an overwhelming lack of evidence."

Either way, the lack of a definitive reason for a baby's death after a long, anxious wait leaves many parents frustrated.

"They told me an autopsy was the only way they could tell me why he died. But really, all it did was tell me that it was SIDS. With SIDS, the autopsy can't tell you why they died," said Brandy Hazel of Lubbock, Texas, who lost her almost-3-month-old son, Cole, to SIDS in July 2006.