A key witness to a daylight street robbery in Lichfield is being sought by police.
The man ran up to a woman before grabbing her necklace and running off.
The incident in Lichfield on September 29 echoed others on the same day in Burntwood and Norton Canes.
A suspect has been arrested and witnesses have come forward, but police say a courier van who gave chase in Lichfield could hold key information.
A Staffordshire Police spokesperson said: “The driver returned to the scene shortly after, saying that he had seen the robbery suspect jump into a waiting blue Audi which then drove away.
“We would like to identify the driver of the courier van, as his statement would be key evidence in the case against the suspect we arrested in connection with all three incidents.”
Anyone with information is asked to call Staffordshire Police on 101, quoting 368 of 29 September.