Thomas Hayward and Alison Simmons worked at the Build-a-Future Independent School in Boston.
Adam Webb also "encouraged pupils to use a dead animal as a ball", a misconduct hearing ruled.
Two unset pole traps and containers of alphachloralose were found during a police investigation.
Shaun Emmerson stabbed Christine Emmerson at their home thinking people "wanted to kill" him.
Christine Emmerson was stabbed multiple times with a kitchen knife at her home in Lincolnshire.
Christine Emmerson, 71, was found dead at a house in West Ashby, near Horncastle, on Thursday.
Shaun Emmerson, 50, has been charged with murder after the death of Christine Emmerson.
A man has been arrested after the woman was found at a property with suspected knife wounds.
Police appeal for witnesses after two men die in separate crashes on Sunday in Lincolnshire.
