The Coast Guard’s remotely operated underwater vehicle was kept in the water until midnight on Tuesday, said police spokesman Lars Bröns.
The search resumed at 7am on Wednesday. By lunchtime the search team had drawn near to Skanstull and the bridge linking Stockholm’s south island with the suburbs.
Last Thursday, police search dogs indicated that there appeared to be a human body in the water in the Norra Hammarby Hamnen area of the city.
Aherne, 32, an accountant from Wicklow Town in Ireland, has been missing since leaving a Stockholm restaurant for a cigarette on the evening of March 15th.
John Aherne came to Sweden to celebrate the St. Patrick’s weekend with his close friend Karl Lambert.
The two men went out with friends on Saturday night and had a few drinks together at a city centre pub.
When Aherne decided he was ready to go home, Lambert stayed behind and gave his friend a set of spare keys.
Aherne stopped off at the Orion restaurant on the ground floor of Lambert’s apartment building on Katarina Bangata in south-central Stockholm.
Aherne had a drink at the restaurant. Leaving his coat on a chair and his phone on the bar, he went outside. He has not been seen since.
Anyone with information relevant to the case is advised to call the police at 114 14.
The Local will publish a more comprehensive update later on Wednesday afternoon.