Police investigating the murder of a nine-month-old baby girl whose body washed ashore on a Gold Coast beach cannot rule out charging her mother over the death.

More than a week after the baby was killed, police on Monday were scouring the Tweed Heads river and surrounding areas for evidence.

They want to find a red and black picnic-style blanket that could have washed ashore somewhere between Tweed Heads and the Gold Coast.

Detectives believe the baby girl was drowned in the area of the Jack Evans harbour at Tweed Heads between 6pm and 7pm on Saturday 17 November.

The girl’s body is believed to have drifted for almost 30 hours before washing ashore on Surfers Paradise beach, where it was found just after midnight on the following Monday.

Her father, who cannot be named for legal reasons, has been charged with murder and appeared by video link in Tweed Heads local court last week.

New South Wales police chief inspector Wayne Walpole said Monday’s tidal conditions were similar those on the night of the girl’s death.

Water police and divers were due to search the Tweed river and foreshore areas while others scoured foreshores and parkland around Jack Evans harbour and Cunningham Park.

Police were conducting dives in line with tidal and current flows to try to determine what happened.

They have asked for anyone who was in the area on the night of 17 November to come forward.

Walpole said there was significant storm activity on the night the girl died and appealed to any storm watchers who might have seen the baby, her parents or her older brother to contact police.

Police have obtained CCTV footage from surrounding high-rise buildings and want to hear from anyone who might have relevant mobile phone or dashcam footage.

“We are interested in speaking to anyone who has seen those people or had interactions with those people to come forward,” Walpole said.

“We would ask for anyone who thinks they saw something, they might not think it’s important or significant but a very small piece of what they see could be very important to the investigation.”

Asked if the girl’s mother could be changed, Walpole said it could not be ruled out.