Police leading the search for missing Belfast schoolboy Noah Donohoe described the recovery of his backpack as a significant development.
PSNI Superintendent Muir Clark revealed that the green backpack, containing the 14-year-old’s laptop and a book, is now being forensically examined by specialist teams.
Superintendent Muir Clark said the discovery was made following a call from a member of the public.
Members of the public who think they have information about Noah can now use the PSNI's major incident public portal, an online reporting platform
Superintendent Muir Clark said: "I want to stress that the activation of the MIPP does not mean that police think a crime has been committed. The investigation into the teenager’s disappearance remains very much a missing person enquiry at this time.
Earlier on Friday, the detective also said a 26-year-old man has been arrested following a social media post about the St Malachy’s secondary school pupil.
The man was detained on suspicion of improper use of a public electronic communications network.
During a press conference on Friday, Superintendent Clark said: “I have previously commented about various rumours circulating about Noah’s disappearance.
"I explained that this type of commentary and rumour was distressing for Noah’s family and unhelpful as we continue our search to find Noah.
“Last night we became aware of social media posts. We are aware of the content of these social media posts and are content at there is no truth behind their content."
Noah's bicycle, helmet, training shoes, mobile phone and other items of clothing have already been recovered but, despite an intense search operation now in its fifth day, nothing has emerged to indicate his whereabouts.
“Our search for Noah continues," Superintendent Clark added.
"We have not yet found his khaki green North Face coat and grey sweat shorts."
“We need to find these outstanding items. If anyone has found any of these items and not yet come forward, please call us immediately on 101.
“Again, I would like to thank everyone who has contacted police so far with information. If you have any information that you think might help. If you have any CCTV or dashcam footage that you think might help and have not yet come forward, please call us on 101 straight away."
Noah was last seen at 6.11pm on Sunday. He had cycled along Northwood Road, where he abandoned all his clothing before being spotted a short time later cycling while naked.
Police believe he then dropped his bicycle and left the area on foot.
Earlier, Belfast's deputy lord mayor has voiced concerns that disturbances and anti-social behaviour by young people in north Belfast is diverting police resources away from the search.
SDLP councillor Paul McCusker was speaking on Thursday night as the fourth day of searching for the 14-year-old St Malachy's College pupil drew to a close.
As searches resumed on Friday morning, Sean McCarry, of the Community Research Service urged the public to remain alert. He said the public should not assume Noah may be confined to the area around north Belfast where the main searches have taken place.
"We have to also assume here that Noah could have moved into other areas and not know where he is or be confused," he told the BBC.
"So anywhere in Belfast, people keep your eyes open and have a look in your house and garden to see there's nobody there that shouldn't be there."
In recent weeks there have various incidents of anti-social behaviour in north Belfast, with large crowds of youths gathering in parks and green spaces, drinking alcohol and verbally abusing nearby residents.
Paul McCusker said a youth was injured in the Waterworks park on Thursday night following further clashes and was advised to attend hospital.
"I am appealing to all young people to remain calm. There is no support for these clashes at the Waterworks and someone is going to get seriously hurt and this is diverting vital PSNI resources away from searching for young Noah," he said on social media.
"Thanks to staff from the Holy Family YC, North Belfast Area Project for their assistance tonight. I am urging all young people as we enter into the weekend not to gather in large groups and think about the impact that drinking alcohol and anti-social behaviour is having on the community at a time when there is a major search going on.
"Not all young people are involved but we need to encourage those involved to stop this immediately."
Speaking to the Belfast Telegraph on Thursday, Noah's distraught mother Fiona said her son would have been the first to join in the search in a similar situation.
"So many people have been out looking for Noah and that has meant so much to me," she said.
"The community has really come together during the search and it has been a great comfort.
"Noah was all about community. If Noah was here and a child had gone missing, he would have been the first person out looking for them. That's the kind of boy he is."