Constable Glenn Matheson, of Te Anau, told an inquest into Ms Osborne's death at Te Anau yesterday, that she and Mr Patterson left Milford Sound on April 4 and were dropped off at the base of Mitre Peak, intending to climb to the summit, which was 1692m.
Mr Patterson had 10 years' experience climbing and Ms Osborne was also experienced, he said.
On the first day Ms Osborne had begun to slow, so the pair set up camp after about five hours.
They left the campsite at 5am on April 5 and reached the summit at 10am.
The last 100m was covered in mist and the descent was carried out under poor visibility.
At about 1450m, Mr Patterson lowered Ms Osborne down a 30m rock face, using a climbing rope.
She landed, untied the rope, and walked off, while Mr Patterson pulled the rope back up.
"The rope got caught in the rocks due to it having a knot in it," Const Matheson said.
"This was unusual because Ms Osborne was usually careful about that."
About a minute later Mr Patterson heard Ms Osbourne scream and saw her fall down a steep ravine from 1417m.
After setting off his emergency locator beacon, Mr Patterson climbed down and then rappelled three stages before seeing her.
"He got near to her and could see she had suffered head injuries and [there was] no sign of life".
When asked by Ms Osborne's family, Mr Patterson said he accepted responsibility.
"I'm always going to blame myself ... ultimately it is my responsibility every 'i' is dotted and every 't' is crossed.
"There were a number of aspects I didn't consider - one was her long-term fitness. In terms of Lynne's general levels of fitness ... I think I may have been a little bit short in that respect. One moment she was moving well, strong ... and the next she was [not]. It was exposed, it was difficult, but it wasn't that difficult."
Southern Region coroner David Crerar found Ms Osborne died from multiple traumatic injuries after losing her footing and falling about 200m.
Mr Crerar said his formal written findings should be circulated among the climbing industry as a reminder for "when the consequences of a fall are likely to be fatal".
Mr Crerar noted Ms Osborne was "in no way compelled" to carry out the climb.
"Lynne was doing something she wanted to do, enjoyed doing it and was given ... the opportunity to stop at any time if she felt it was beyond her."
Const Matheson said an initial attempt to locate Ms Osborne on the day of the accident was unsuccessful due to cloud cover, but a Southern Lakes Helicopter attempted again that afternoon, locating Mr Patterson about 4.30pm.
Mr Patterson told the inquest he had raised concerns about Ms Osborne's food intake the day before her death, with her snacks consisting of raisins and salads, with a dehydrated meal for dinner.
She appeared to take his concerns on board and the following day ate muesli bars instead.
While she had said she was tired on the first day, she was strong and sure in her movements, was not wobbly and was coherent.
Her energy levels were fine throughout the second day of climbing, until she said she was tired and had a headache.
I asked if she wanted to rest and she said she didn't think that would help.
I asked "are you feeling wobbly?" and she said "No".
