The driver of an orange Renault Megane involved in the collision on the A16 at Stickford has died in hospital.
Police are renewing our appeal to motorists who were using the A16 near to Stickford on Friday at around 4.35pm.
The 27-year-old was originally airlifted to the Queen’s Medical Centre in Nottingham.
A spokesman said: “We are particularly interested in speaking to anyone who saw an orange Renault Megane and a red Vauxhall Astra being driven on the A16 away from Boston.
“We would like anyone who saw the vehicles being driven in the Boston area before the incident, or anywhere along the A16, to contact us.”
Sgt Chris Dennett, from the Serious Collision Investigation Unit, said: “This is a very tragic collision. To help with our investigation I appeal for anyone who saw these vehicles on the A16 or in Boston to call in.”
A 39-year-old local man who was arrested in connection with this incident has been released on police bail until November.
Anyone who saw either vehicle being driven in Boston or along the A16, or the collision itself, is asked to call the Witness Collision Line on 01522 885588.