Police have shared the "breakthrough" moment which led them to catch the brutal killer of a beloved primary school teacher.
Sabina Nessa, 28, was killed in an "appalling murder " committed by "evil" sex predator Koci Selamaj, 36, last year.
Metropolitan Police have now shared the meticulous investigative work which led officers to capture Selamaj in his home town, located 70 miles from where the teacher was attacked.
Senior Metropolitan Police Detective Chief Inspector Neil John said time was the greatest enemy the police faced when hunting down the killer behind Sabina's "heinous" murder.
He said police were determined to catch the killer before he potentially struck again.
Sabina was killed in a park in Kidbrooke, south-east London, in September 2021.
Horrifying CCTV footage showed him brutally striking the 28-year-old over the head 34 times until she was rendered unconscious.
The evil sex predator carried away her body, strangled her, removed some of her clothes and then attempted to hide her body.
The garage worker from Eastbourne, East Sussex, travelled up from London - miles from his home to commit the atrocious murder.
Officers learned from Sabina's friends that she was uncomfortable using the park as a cut-through, but had been running late for a meeting at a local restaurant the night before.
Mr John said: "In this case we were very lucky in many respects that the incident - which is shocking and harrowing - was caught on camera."
Describing the grainy images, he said: "Selamaj had entered the park 22 minutes earlier, in effect skulking in the shadows, looking to see who came into the park.
"Sabina unfortunately crossed paths with him.
"As they passed each other on the pathway, he carries on walking for a short period of time, turns, looks, there is a momentary glance, and runs back to Sabina.
"He has run at her at a rapid pace and, just as he is upon her, I would suggest that she has heard footsteps behind her and, as she started to look around, he has gratuitously struck her over the head with a red warning triangle 34 times in quick succession.
"That has rendered her unconscious over a park bench. And he has manhandled her up a grass bank and out of sight.
"The imagery then shows there was a gap of 10 minutes where he and Sabina are out of shot.
"Then we see him coming back down to the park bench where the assault took place and picking up bits from the floor - the warning triangle.
"He then goes out of sight for a further 10-minute period and then he reappears back at the bench where he is seen to attempt to wipe down the bench with tissues."
CCTV taken of the "savage" attack shows Selamaj "casually" walking away with his hood up at 8.56pm.
He was not identifiable from that footage, according to Mr John, but trawling through CCTV led to a breakthrough.
The Met Detective said: "A couple of days on, one of the officers identified a glint or something reflective in the top corner of the park a short time after the incident.
"We were able to focus our efforts on the direction he was going."
Police identified Selamaj's car parked in a side road and an image of the attacker was released to the public.
He had gone to a local Sainsbury's, where he bought a rolling pin, chilli flakes, an energy drink and a "bag for life".
In the end, he swapped the rolling pin as a potential weapon with the reflective warning triangle.
Traffic cameras were used to track Selamaj's car on the A2, enabling police to retrace his journey to Kidbrooke from Eastbourne and back again.
He arrived in south-east London at 7.41pm and left at 9.01pm, spending just an hour and 20 minutes in the area.
From the registration details of the suspect car, police identified Selamaj as the owner and officers were dispatched to his home in Eastbourne.
Selamaj was arrested in an early-morning raid on his home and taken into custody.
Mr John said he "barely uttered a word" and was "calm and collected" throughout, despite having no previous convictions or cautions.
His mask only slipped twice - when his cell door closed in Eastbourne custody suite, he could be seen, head in hands, pacing up and down "as the enormity of what he had done began to sink in".
He also put his head in his hands when he was charged and, being told of the caution through a translator, the Albanian garage worker said: "What will happen if I open up now and say everything?"
On examining his return journey, police found an eight-minute deviation near Tunbridge Wells in Kent which should have taken two or three minutes.
Kent Fire and Rescue Service was called in to help search the verges and "throwing distance" around Dundale Road - and on the second day of that search, the warning triangle was found dumped in the River Teise.
Mr John said further evidence revealed that the murder was pre-meditated and sexually motivated.
He said Selamaj had booked a £350 room days earlier at the Grand Hotel in Eastbourne, where his estranged wife worked.
Staff there became concerned and reported the booking to 101 and Mr John said staff were "uncomfortable with his demeanour" and the fact that he lived nearby.
He said it would have been a "difficult conversation" for the operator, but suggested they did the right thing by explaining "there was no cause for concern at that time".
Mr John described Selamaj as an "evil coward", adding: "It is highly unusual for someone to go from zero to a crime of this magnitude.
"We are pleased Selamaj will spend the majority of his life in prison."