The tour bus was packed with 57 passengers and was bound for Copenhagen when it flipped. One person died at the scene and 40 others were rushed to hospital, while the driver of the vehicle subsequently succumbed to his injuries.
"We want to take a closer look at what happened," Jonas Bäckstrand, chairperson of the Swedish Accident Investigation Authority (Statens Haverikommission) told the Borås Tidning.
In the wake of the accident the sister of the deceased bus driver said the crash happened because her brother had taken a stroke at the wheel.
She told the Expressen newspaper that her brother, who was in his 70s, could not be "held responsible" as a result.
Bäckstrand said he was aware of the recent media reports regarding the bus driver but said he was unable to comment on them.
The investigation is expected to examine factors such as the condition of the road and the construction of the bus, which may have had an influence on causing the fatal crash.
Staff have already begun carrying out analysis at the accident scene and are working closely with rescue services and the Swedish Transport Administration (Trafikverket).
The investigation is expected to take up to a year to complete.
"It's a long process," added Bäckstrand.