After examining the scene of the latest mass sheep killings, police believe both cases involve firearms.
Police today examined the North Otago farm were 20 sheep were killed, just days after 195 sheep were shot dead on a nearby property.
The latest killings in the Ngapara area occurred Sunday night or in the early hours yesterday morning.
Detective Warren Duncan said there were similarities between this case and the killings at Peter and Janine Stackhouse's Ngapara farm, including both appeared to have involved a firearm.
He said the cases "may be linked", but police were still determining whether that was the case.
Duncan said the "unusual events" had caused concern among locals. "Our advice to farmers is to check your stock more regularly than usual and if possible, although it's not always practical, move your stock to paddocks that might be closer to your home.
"Keep in close contact with your neighbours, talk with them and look out for each other."
Oamaru Police were seeking information on any suspicious vehicles or people in the Crown Hill, Conlans Rd and Peaks Rd areas overnight on Sunday or early yesterday.