A £10,000 reward is being offered for information about a spate of deliberate fires in Greenock.
The attacks have left a man dead and a mother seriously injured.
Several properties and a car have also been destroyed in a series of incidents that police believe are likely to be linked.
Angela Parker, Scotland National Manager at the charity Crimestoppers, said: “To put lives, especially children, at such risk is appalling and sickening.
“One poor man has already lost his life. Whoever is responsible must be stopped before someone else is harmed or killed by this reckless behaviour.
“Our charity, which is independent of police, is supporting officers by launching an urgent appeal for anonymous information about whoever is behind these attacks. We are also putting up a reward of up to £10,000 given the urgent nature of the investigation.”
Crimestoppers believe there may be people in the local community who know or have suspicions about who is behind the attacks.
The first incident occurred on 14 September when a 46-year-old man died at a property on Greenock’s Union Street.
Two days later, a flat in Wellington Street was firebombed. A girl who was in the property at the time was unharmed but her mother was badly injured as a result of the fire.
A stolen Suzuki Splash vehicle, which is thought to be linked to the firebombing, was discovered burnt out in Skye Street.
In a separate incident on 19 September, a house in Cumberland Road was targeted with a suspected petrol bomb.
Residents were also evacuated when a fire was deliberately set at a property in Kincaid Court on 28 September.
An electric blue coloured vehicle, possibly a BMW, was seen in the area when the fire was started.
Anyone with information is asked to phone Crimestoppers on 0800 555 111 or via the simple and secure anonymous online form at www.crimestoppers-uk.org