A flooded quarry has been drained as part of an investigation into the disappearance of a woman and her young son more than 40 years ago.
Renee MacRae, 36, from Inverness, and her three-year-old son Andrew disappeared on 12 November 1976.
An estimated 13 million litres of water has been pumped from Leanach quarry at Culloden, near Inverness.
Silt and debris at the bottom will now be removed and taken to another location for forensic tests.
Detectives announced last month that they intended to drain the quarry in an effort to solve the mystery. It was searched in the months following the disappearance of Mrs MacRae and Andrew.
Police have been treating the case as a murder inquiry.
On the evening of her disappearance, Mrs MacRae, who was estranged from her husband Gordon, had set off for Perth with the youngest of her two sons, Andrew, to meet her lover Bill McDowell, Mr MacRae's married accountant.
He told police they never met.
Mrs MacRae's burnt-out BMW car was discovered on the night she disappeared in a lay-by on the A9 south of Inverness.
Det Insp Brian Geddes, of Police Scotland, said an "incredible" and "tireless" operation to drain the quarry meant detectives could start the "detailed searching phase" of the operation.
He said: "Pumping the water clear was a huge challenge, but we have made fantastic progress in a very short time.
"Silt and debris from the bottom of the quarry are now being removed by lorry to undergo forensic tests at another location.
"The whole team remains extremely confident that vital evidence we believe was hidden in Leanach will be recovered in the coming weeks.
"I want to reassure the family and friends of Renee and Andrew that we will not be leaving here until every last inch is searched."
Renee and Andrew MacRae: Timeline
17:00, 12 November 1976: After dropping off her eldest son, Gordon, at Mr MacRae's home, Mrs MacRae and Andrew leave Inverness for Perth.
22:00, 12 November 1976: Mrs MacRae's BMW car is found on fire by a passing bus driver about 12 miles (19km) south of Inverness. The car is parked on a loop road that was being used as a lay-by during the construction of then new A9 trunk road. Blood is found in the boot of the car. But there is no sign of the mother and son and police begin what would become one of the UK's longest missing persons investigations.
1976: In the fortnight following 12 November, more than 100 police officers and large numbers of volunteers search moorland around the site of where the car was discovered. RAF Canberra aircraft make wider sweeps of the area.
1977: Divers search flooded Leanach Quarry, a known fly-tipping spot, near Inverness.
August 2004: Police return to Dalmagarry Quarry, which was searched at the time of the mother and son's disappearance. Northern Constabulary drafts in forensic archaeologists and anthropologists to sift 35,000 tonnes of soil from the disused quarry, near the lay-by where Mrs MacRae's car was discovered, but no sign of the mother and son is found. New tests are also carried out in a laboratory in Aberdeen on traces of blood found in the boot of the BMW.
2016: A report naming a suspect who may have killed the pair is sent by Northern Constabulary to prosecutors but they decide there is insufficient evidence to take action.
October 2018: For about a week, Police Scotland divers examine Leanach Quarry using a remotely operated vehicle.
9 October: To mark Andrew's 45th birthday, police release a photograph of him and an image of the Silver Cross pram owned by his mother. Officers appeal for sightings of the pram on and around 12 November 1976.
28 May 2019: Work to pump water from Leanach quarry begins.
10 June: Leanach quarry is drained clearing the way for silt and debris to be removed for forensic tests.