A 51-year-old man has been arrested on suspicion of causing death by dangerous driving after a body was found on the A40 in the early hours of Thursday morning.
The crash happened on the main road passing intelligence agency GCHQ’s headquarters, known as “the Doughnut” on the outskirts of Cheltenham.
Police closed the road until 6.30pm on Thursday as officers carried out investigations.
“Last night a 51-year-old man from the Newport area was arrested on suspicion of causing death by dangerous driving. He remains in custody this morning,” a spokesperson for Gloucestershire Constabulary said.
“Several members of the public called police yesterday to report concerns that a missing 27-year-old Cheltenham man could be the victim.
“While formal identification has not yet taken place, officers remain in contact with the family and a specialist family liaison officer is offering support.”
There is no indication that either the driver arrested or the victim were employed by GCHQ.
The suspect is the second person to be detained in connection with the investigation.
A 62-year-old man, who was also held on suspicion of causing death by dangerous driving, has been released under investigation.
Investigators are appealing for information from passing motorists, including a people carrier-type taxi and motorbike that were driving along the A40 towards Cheltenham at the time.
Anyone with information is asked to call police on 101 and quote incident 40 of 16 August.