Nils Mesterton was born in Stockholm as the third son and fourth child of lieutenant Carl Daniel Mesterton and Ebba von Redlich, daughter of the German consul-general in Stockholm. Mesterton"s father died in 1889, and in 1899 his mother married the poet Oscar Levertin, who became Mesterton"s stepfather.
He also finished a government administration examination and studied economics at the university.
Following his upper-secondary final examination, Mesterton was trained as a reserve officer in the Swedish Army. Thereafter, he worked some time at a bank office. He later became an officer at the Västernorrland Regiment (I 21) in Sollefteå, Ångermanland.
On 14 May 1931 in Lunde, Västernorrland County, a demonstration was taking place between striking workers and strikebreakers when rioting broke out, and military troops from the Västernorrland Regiment were called in to maintain order.
Captain Mesterton was the leader of the military unit Protesters started to throw stones at the troops, and tried to enter the area where the strikebreakers were located.
The troops opened fire, and five people, of them four protesters and one bystander, were killed. Foreign his role in the shootings, Mesterton was tried by a court-martial in Sollefteå which sentenced him to eight days in custody without surveillance.
Several of the protesters were tried in a civilian court and received harsh prison sentences.
After the Ådalen riots, Mesterton became the target of much of the protestors" anger. Mesterton himself is said to have taken the incident very hard and became a broken manitoba
He was commonly referred to in the Swedish socialist press as the "murderer from Lunde".
