A "miscommunication" led a teenage girl and her mother to leave the teen's 6-month-old daughter at a SEPTA station, the transit agency's police chief said.

The child was left at the 60th Street station on the Market-Frankford El on Monday morning after her mother went through a turnstile and boarded a train, while the child's grandmother left the station.

SEPTA Transit Police Chief Thomas Nestel said the baby's mother and grandmother walked to the El station together each morning, the 15-year-old mother would get on a train to go to school and the child's grandmother would take the baby home.

There was no school Monday, and the two were supposed to go to an aunt's house together, Nestel said.

"There was a miscommunication about who was going to take the baby," he said. That misunderstanding was compounded further, Nestel said, because the two women may have been trying to use the same one-day convenience pass, which allows one person to take eight SEPTA rides on a given day.

The 15-year-old is believed to have handed the baby's grandmother the pass after she went through the turnstile. The grandmother then used a convenience pass at another station.

Neither is facing charges for fare evasion or leaving the child. Nestel on Tuesday defended his officers' decision not to arrest either woman.

"It's clear they didn't intend to leave the baby behind," he said. Nestel said food and both women's purses were left in the child's stroller. "It's very clear that this was an accident."

He said the pair's accounts differed on whether the two were trying to game the SEPTA fare system and officers couldn't prove that both used the same pass.

A SEPTA cashier retrieved the baby. The girl's mother and grandmother realized at the next station that neither of them had the child.

The baby's mother and grandmother "were very frantic about the whole situation" and "probably learned a better lesson than us citing them," he said.

Contact Emily Babay at 215-854-2153 or ebabay@philly.com. Follow @emilybabay on Twitter.
Contact the Breaking News Desk at 215-854-2443; BreakingNewsDesk@philly.com. Follow @phillynews on Twitter.