Debbie Duncan told the Guardian she still believes something bad might have happened to her son.
She flew to the Spanish island on Tuesday, the day after her 19-year-old son went missing, to assist in the search for him.
On Saturday, the sixth day of the search, police, rescue dogs, and firefighters gathered again at Rural de Teno Park, where Mr. Slater's phone was last tracked.
Ms. Duncan told the Guardian that police mentioned the attention around the case was impacting their investigation, but she feels they are intensifying their search efforts.
This follows reports of someone accessing Mr. Slater's Instagram account who wasn't him.
Rachel Louise Harg created a GoFundMe page for search expenses and a Facebook page to aid in locating him, raising over £26,000 of its £30,000 goal by Saturday afternoon.
She described those who had been hacking the social media accounts of Mr. Slater's family as "sick."
Ms. Duncan said police assured her they were "investigating all leads" and had detailed plans and locations.
She reiterated the need for British police assistance in the search, citing difficulties with the language barrier.
Spanish police declined an offer from Lancashire Constabulary to assist, stating the case is outside UK policing jurisdiction. However, Lancashire Constabulary offered support with additional resources if needed.
The force stated that Spanish police have confirmed they currently have sufficient resources but would reach out if they require assistance in the future.
Mr. Slater is from Oswaldtwistle in Lancashire, where specialized officers are continuing to assist his family, according to the force.
The apprentice bricklayer was on vacation with friends in Tenerife before he disappeared and had attended the NRG music festival on Sunday.
He last contacted his friend Lucy Law just after 8am on Monday, telling her he was starting an 11-hour walk home after missing a bus.
She mentioned he informed her that he was lost, needing water, and had only 1% battery left on his phone.
SOURCE: Sky News