A man killed himself, his wife and three young girls after he faked a Covid-19 jab certificate and feared his children would be taken away when it was discovered.
Police found two adults, both 40, and three children aged four, eight and ten dead from gunshot head wounds in a family home in Koenigs Wusterhausen south of Berlin on Saturday.
In a pages-long farewell note found by police, the man, named as Devid R, said he forged a vaccination certificate for his wife Linda.
Her employer had found out, prompting the couple to fear they would be arrested and lose their children Leni, Janni and Rubi, prosecutor Gernot Bantleon told news agency dpa.
Police were called to the house on Saturday after being alerted by witnesses who had seen lifeless bodies in the house. Pictures of the young family alongside candles and teddies were left outside the property in tribute.
Submitting a fake Covid-19 vaccine certificate became a criminal offence two weeks ago and is punishable by either a fine or a years jail term.
Investigators suspect that the man killed his wife and children and then himself. They found a gun in the house, but it wasn't immediately clear whether it was the weapon used to fire the fatal shots.
They found no indication that anyone else was present at the time or that anyone forced their way into the house.
Police said autopsies on the five bodies were underway and will determine how long the family had been dead.
The grisly case comes as Germany has been tightening up restrictions to try to stem a fourth wave of the coronavirus pandemic.
The incoming German government wants to make Covid-19 vaccinations mandatory from March 16 for people working in hospitals, nursing homes and other medical practices.
A draft of the legislation seen by Reuters said staff working in these areas would have to prove that they are vaccinated or recovered from COVID-19 or present a medical certificate to show they cannot be vaccinated by March 15.
Meanwhile, from last month, employees have been required to show they are vaccinated, recovered or test negative for Covid-19.
German authorities agreed last week to bar the unvaccinated from access to all but the most essential businesses such as grocery stores, pharmacies and bakeries.
Meanwhile nightclubs and music venues in areas where the incidence rate is higher than 350 will be forced to close.
Outdoor football stadiums will be limited to a maximum of 15,000 spectators while indoor venues will be capped at 5,000.
Schools students will have to wear masks while private gatherings for unvaccinated people will be limited to one household.
The Bundestag also last week debated a nationwide vaccine mandate with a view to making it law by February next year.
Members will vote on the bill in early 2022. Outgoing Chancellor Angela Merkel has thrown her weight behind the move.
Just 69 per cent of Germany's population is vaccinated, lower than the 74.2 per cent who have had both jabs in Italy and the 70.5 per cent in France. Meanwhile 69.3 per cent of the UK's population have had both jabs.