The first death took place on Sunday night, when a pensioner was attacked at his home in Devon.
Police were called to a property in Kingsteignton at 9.20pm, where they found the 73-year-old suffering multiple stab wounds.
The pensioner was taken to Torbay Hospital where he was confirmed dead.
It is understood that a family member saw the attack, which was described by Detective Superintendent Mike West of Devon and Cornwall Police as "random".
On Monday morning, officers were called to a car near Labrador Bay, Shaldon, where they found the body of a man.
Police are appealing for information on both deaths and have also asked for anyone who may have seen a blue Skoda Fabia in the area on Sunday or today to come forward.
Speaking about the attack on the pensioner - who has not been named - a neighbour told the DevonLive website: "It happened just at pub closing time so it was pretty busy, there were crowds of onlookers gathering at 11pm, some of them were in their dressing gowns."
Another neighbour, who did not want to be named, said: "It's just awful. We're not just neighbours, we're all friends down here.
"There's only a few houses in this little close. It's only a tiny road but we know nothing."
Detective Chief Inspector Roy Linden said the investigation was "a rapidly evolving situation".
He added: "Additional resources are being used from across Devon and Cornwall with the priority of identifying those responsible, and as a result the residents of Kingsteignton can expect to see an increased police presence in the area.
"We would also take this opportunity to reassure everyone that this type of incident is rare."
:: Anyone with information is asked to call 101 or email [email protected] quoting log number 836 9 June.