Missing Kyle Vaughan: Man, 24, and woman, 22, released on police bail
Police have released on bail a 24-year-old man from Blackwood arrested on suspicion of murdering missing Kyle Vaughan.
A 22-year-old woman from Newbridge arrested on suspicion of perverting the course of justice has also bailed.
Mr Vaughan, 24, was last seen alive three weeks ago and is feared dead. His car was believed to have been in a collision the night he disappeared.
Gwent Police say they are continuing their inquiries into his disappearance.
Officers have now made six arrests in their investigation.
Another man aged 27 was arrested on suspicion of murder.
Two other men, aged 21 and 15, were later arrested on suspicion of assisting an offender and a 62-year-old Newbridge man was also arrested on suspicion of perverting the course of justice.
Those arrested have all been released on police bail.
The missing man's parents Alan Vaughan and Mary Lucas have said they believe witnesses were "too scared to come forward".
Both believe information vital to the police murder hunt is being held back by people fearful for their own safety.
Rock music fan Mr Vaughan, who has diabetes and needs regular insulin injections, is believed to have been last seen alive in the Abercarn and Risca areas of Caerphilly county late on 30 December.
Later that night his car, a silver Peugeot 306, was found on the A467 between Risca and Crosskeys. Police said it was believed to have been in a collision.
Mr Vaughan is 5ft 8in (1.72m) tall, with a slim build, and short dark hair and brown eyes.
He was known to wear a gold neck chain with a cross and has a distinctive tattoo of a pair of flaming dice on his inner left forearm and tattoos on his right leg.
Gwent Police have asked anyone with information to call 101, 01633 838111 or Crimestoppers on 0800 555111.