Conner Marshall was killed in an unprovoked attack by David Braddon, who was on probation.
The hospital reportedly demanded fingerprints and samples of handwriting to find the whistleblower.
The Labour MPs set out their pitches, as they and other contenders prepare for the first hustings.
The actor played Bernard in Yes Minister and was in the entire series of Heartbeat.
Equalities minister Victoria Atkins says "common sense" is needed to determine what counts as harassment.