It's expected more people will be arrested in relation to the death of Palmerston North man Hori Gage

The 27-year-old was fatally shot in his car in front of his partner and children last August.

A vehicle believed to have been used to flee the scene was found burned out.

Yesterday, Police arrested four people -- three in relation to the fire and one charged with being an accessory to manslaughter.

The new arrests come after two people were taken into custody in January - one with injuring with intent - and one with wounding with intent to cause grievous bodily harm.

Eight full time police staff are working on the investigation.