The FBI has joined the search for a newborn baby girl after the child's father returned home to find her mother had been shot dead, police said.

The man came home from work in Wichita, Kansas,on Thursday to find that Sofia Victoria Gonzalez Abarca was missing, and her 27-year-old mother was dead, police Lieutenant Todd Ojile said, reported Fox News.

Police are not treating the father as a suspect in the murder, and believe the child's life may be in danger, Sgt Nikki Woodrow added.

The child was just six days old when she vanished.

The mother has been identified as Laura Abarca-Nogueda, reported KWCH12. Police said that the last known contact with her was made at 1pm local time, and police were called at 3.30pm, so she was likely killed between those times.

Police have interviewed friends and family of the victim but so far have uncovered no new leads.

On Friday, a specialist FBI child abduction team joined the investigation.

Police said that the driver of a purple Cadillac considered a 'person of interest' had been found and questioned, and was not a suspect.