Police in Cumbria trying to find a missing teenager and her baby son say they want to trace a woman who is believed to be the last person to speak to her.
Catalina Covaci, 15, disappeared with six-month-old Ricardo on December 19.
But CCTV cameras at Manchester Piccadilly Station videoed her speaking to a woman.
Police say they want to speak with the woman, who is the last person known to have spoken to the mum before she vanished.
They spoke at around 1.40pm on the afternoon of December 19, 2012.
The woman is described as wearing a black jacket, a black hat and carrying several bags.
Detective Inspector Furzana Nazir said: "It is incredibly important that we trace this witness to find out what Catalina said, whether she asked for help or whether she indicated where she may be going.
"We are into the fourth week of her disappearance and concerns are mounting. Her family in Penrith are distressed and we need to ensure that we locate them both – quickly.
"Please, if you were travelling through Manchester Piccadilly on Wednesday 19 December 2012, take a look at this image and see if it was you. Were you travelling home for Christmas? Did you see or speak to a young mum pushing a black pushchair through the station around lunchtime?"
Anyone with information about the case to call Cumbria Police on 101 or Crimestoppers 0800 555 111.