You could almost always get away with the murder.

In Sweden and Finland you needed full fine, 40 marks in silver (10 kilograms, Swedish silver mark was 249 g) and oath of twelve men that were present when the murder happened. The fine was divided in three parts, one third to relatives, another to king, third to hundred. If you could not get enough jurors, you could claim self-defence and bribe the relatives of the victim to beg king for clemency. A murderess could be spared by the relatives even if she could not pay the full fine to king and hundred.

There were some wicked deeds that you could not fully compensate with weregild: if you killed your father or mother, brother or sister, daughter or son, a child younger than 7 years, a man sleeping or fording/swimming, or somebody else's thrall on the road.

There are no consistent medieval sources from Finland, but in 1540–1620 there were 169 murder cases and 3–4 executions. Rest of the cases were settled with weregild.

If a murder (dulga-dråp, salatappo) was left unsolved for one year and a day, the free men of the hundred had to pay the full mordgeld of 40 marks, half to king, half to the relatives. So the hundred had incentive to get a judgement on obvious cases, and pooh-pooh less obvious cases.

So how much was 40 marks? Again, the medieval sources are very limited, but there are complete records of silver tax collected from every freeholder in 1570. In the parish of Suodenniemi the average wealth was 66.6 marks, the richest yeoman was worth of 206.3 marks (and he had 40 marks in coin). A horse was valued 10-20 marks, a mare 5–10.