Police have appealed to taxi drivers and train passengers to remember if they have seen a man suspected of killing his girlfriend and baby.
The family of a murdered woman and baby have said they have been left with a "huge hole" in their lives.
The bodies of Stephanie Bellinger, 24, and eight-month-old daughter Lily were found at their home in Totton, near Southampton, in Hampshire on Saturday.
Stephanie Bellinger, 24, and her eight-month-old daughter Lili were discovered at their home in Totton, near Southampton, in Hampshire, on Saturday.
Police said it was "paramount" Ms Bellinger's boyfriend, Anthony Marsh, 21, was found quickly.
Ms Bellinger's boyfriend, Anthony Marsh, 21, is wanted by detectives in connection with the deaths.
He has been described as dangerous and possibly armed with a knife.
Hampshire police have said it is "paramount" that Mr Marsh is found quickly.
Officers said there had been no news on his whereabouts overnight.
Ms Bellinger and her daughter were found dead inside their home in Myrtle Avenue.
Ms Bellinger died of stab wounds, a post-mortem examination found. Tests on Lily will be carried out on Tuesday.
Her family said: "Stephanie was a fun-loving free spirit who was always happy and smiling.
A police spokesman said her family was expected to release a statement and picture later.
"Stephanie was a wonderful daughter, sister, aunt and mother.
'Missing before'
"Lili was a bouncing, happy little baby who was a delight to be with, a little chatterbox who brought joy to our lives.
Mr Marsh's mother Wendy told her son it was "pointless to run away or hide".
"We now have a huge hole in our lives which we have to try and come to terms with."
He is described as white, 6ft 2in, with short fair hair and brown eyes. He is of slim build and has a tattoo on his left forearm.
Police said he was known to have visited Plymouth, Bristol, Bournemouth, Portsmouth and Brighton by rail.
He is also known to take long walks in the New Forest and had a particular spot he liked to visit between Lyndhurst and Bournemouth, known locally as Devil's Dyke in Burley.
Mr Marsh has gone missing before and is known to sleep rough or in churches.
He has not had contact with friends or relatives since shortly before 0900 GMT on Saturday.
Anyone with information is asked to contact the investigation team at the major crime suite in Hulse Road, Southampton.
