TAMPA — The son of a Lutz fertility doctor killed a girlfriend's unborn child by tricking her into taking an abortion drug, federal authorities said Wednesday.

The act could put John Andrew Welden, 28, in prison for life.

Welden forged the doctor's signature on a prescription for Cytotec, relabeled a pill bottle as "Amoxicillin" and told the woman that his father wanted her on antibiotics, a federal prosecutor asserted Wednesday.

The incident occurred in March after an ultrasound at Dr. Stephen Ward Welden's office confirmed the pregnancy, according to Assistant U.S. Attorney Steve Muldrow.

The doctor, a board certified obstetrician and gynecologist, has not been accused of any crime.

The woman, identified in court documents by the initials "R.L.," wanted to keep the baby even if she had to raise the child without John Welden, the prosecutor said.

"He had no reason to kill the baby, his baby," Muldrow said. "She had a name for the baby she wanted to have."

Muldrow didn't disclose the gender of the fetus or the duration of the pregnancy.

But the stage of the pregnancy won't matter under federal law, which disregards the viability of a fetus in such cases.

The federal Unborn Victims of Violence Act of 2004 defines "unborn child" as "a member of the species homo sapiens, at any stage of development, who is carried in the womb."

If someone kills an unborn child while committing a federal crime, it's considered murder, said Tampa lawyer Todd Foster, a former assistant U.S. Attorney and FBI agent who is not associated with this case.

Welden's first alleged crime? Product tampering, "with reckless disregard for the risk that another person would be placed in danger of death or bodily injury."

A federal grand jury indicted him Tuesday on that charge, along with one count of first-degree murder.

On Wednesday, U.S. Magistrate Judge Anthony Porcelli denied bail after the prosecutor described Welden as a flight risk because of the serious nature of the charges.

Defense attorney David Weisbrod pointed out that Welden had no prior criminal record.

He characterized the incident as an aberrant act.

He said the family was willing to put up valuable real estate to secure his release on bail, pending the case's outcome.

But the judge took note of the possibility of a life sentence. And the government had provided him a preview of a strong case.

Welden admitted his actions in a confession recorded by Hillsborough County Sheriff's Office detectives, the prosecutor said. A drugstore surveillance camera captured the Cytotec purchase.

Cytotec, brand name for the drug misoprostol, is a prostaglandin medicine used to terminate a pregnancy by starting labor, according to the WebMD website. It is also used to treat stomach ulcers.

The woman took a pill on her way to work, then quickly felt abdominal pain and began bleeding, the prosecutor said.

She lost the baby at a hospital.

"What did you give me, Andrew?" she asked Welden, according to the prosecutor.

Welden uses his middle name, Andrew, on his Facebook page, too.

"Please pray for me," he posted there Monday, a day ahead of the indictment.

The Facebook page states that he is an office manager at the Lutz office of Premiere Weight Loss Center, which is a Welden family enterprise.

The center's website states that he studied nutrition and exercise physiology at the University of Mississippi and the University of Memphis, and is working toward a degree in sports medicine.

His father and stepmother, Lenora, sat through Wednesday's hearing, and by the end of it, tears streamed down their faces. The defense attorney, who declined further comment, escorted them to a conference room and closed the door.

"Doc Welden," as his website dubs the father, has practiced reproductive medicine for more than three decades, most recently at a center that caters to infertile couples who hope to become pregnant.

News researcher John Martin contributed to this report. Staff writer Patty Ryan can be reached at pryan@tampabay.com or (813) 226-3382.