Paul Robson, 49, was held near Glasgow, Scotland, on suspicion of murder on Friday.
The arrest came after an attack on English teacher Caroline Kayll, 47, and a boy, 15, at an address in the village of Linton, Northumberland.
At about 8.55pm on Nov 15, Northumbria police received a report that Ms Kayll and the teenager had been assaulted inside the address.
Ms Kayll died in hospital while the teenager, who was not related to her, suffered serious but non-life threatening injuries.
On Thursday, police released details of Robson and said he was wanted in connection with the attack.
Those enquiries focused in Glasgow and now police have confirmed that Robson has been arrested near to the city.
He remains in police custody at this time.
Supt Paul Milner, of Northumbria Police, said: “In recent days our officers have been carrying out enquiries across the region and north of the border.
“Those enquiries have now led to the arrest of Paul Robson on suspicion of Caroline’s murder and the serious assault of a teenage boy.
“We want to reassure the public that this was an isolated incident and at no point were they at risk.
“Enquiries into the circumstances leading up to this attack will continue but we would ask the public to avoid speculation.
“This is a live murder investigation and it is an incredibly difficult time for Caroline’s family and the teenage boy injured in the attack.
“They will continue to receive our full support while we would ask anyone who has information that could assist our investigation to get in touch.”
Tributes to Caroline poured in online, with one parent writing on Facebook: “My son’s English teacher, needless to say he’s devastated. Our deepest condolences to her family and friends.”
Another woman posted: “RIP beautiful lady. Such a tragedy, Caroline was an amazing lady.”
Another wrote “Devastated to hear this. RIP Caroline. Thinking of your family and friends.”
One tribute described her death as “horrendous and awful” adding: “A 47 year old lady has been robbed of her life. My thoughts go to family and friends.”
At Atkinson House School, for pupils with Social, Emotional and Mental health issues in Seghill, Northumberland, a spokesperson said: “Our school community is saddened to hear the news of Caroline’s passing. Our thoughts and prayers are with her family at this very difficult time.”
A 58-year-old man arrested on suspicion of assisting an offender has since been released under investigation.
Anyone who believes they may be able to assist police is asked to report online at the Northumbria Police website quoting log 421 19/11/20.
You can also call police on 101 or independent charity Crimestoppers anonymously on 0800 555 111.