POLICE are searching for witnesses to help piece together details in an investigation into the suspicious death of a woman involved in a crash in the Tweed River last October.

Michelle Lord, 57, died after the silver-coloured Nissan 300zx she was a passenger in crashed into the Tweed River, east of Tumbulgum, about 9.30pm on Sunday, October 18, last year.

The car was travelling in an easterly direction along Tweed Valley Way when it veered into the river about 500m east of Riverside Dr.

When Tweed/Byron LAC officers arrived, the 51-year-old male driver was out of the vehicle and helping 57-year-old passenger, Michelle Lord.

Ms Lord was airlifted to Gold Coast University Hospital in a serious condition but was later pronounced dead on Tuesday, October 20.

Strike Force Coval was established with the help of the Queensland Police Homicide Squad to investigate the incident.

Police executed a search warrant at a South East Queensland home about 10.30am yesterday, where they seized a number of items for forensic examination.

Police have released images of Ms Lord and are appealing for public assistance to piece together her movements before her death.

They have released an image of a vehicle similar to the one involved in the crash.

Anyone who may have witnessed the crash or was in the area at the time is urged to contact Tweed Heads Police Station on 07 5536 0999 or Crime Stoppers on 1800 333 000.