More than 120 pensioners have been arrested on suspicon of committing a criminal offence in St Helens over the four years.
Figures released under Freedom of Information rules show that in 2013/14, 27 adults aged 65 and over were arrested for crimes.
Of these, 22 were aged 65 to 69 and five were aged between 70 and 79.
This figure has fallen from 33 in previous period, which included three OAPs in their 80s and eight in their 70s.
The number of arrests has fluctuated, with 34 in 2011/12 and 27 in 2010/11.
The most serious offence in 2013/14 was rape, where one pensioner was arrested; three for actual bodily harm; and two for wounding.
There were two cases of theft, and two for burglary.
One OAP was arrested over an offence of criminal damage, one was arrested for harassment, whilst five were in trouble for breach of peace.
Three pensioners were reprimanded for being drunk and disorderly and two were arrested for drink driving offences.
Of the 27 pensioners arrested, 10 were charged and sent to court; two were sent to prison; three were given fines and one was given a curfew as part of a community order.
A Merseyside Police spokesman said officers take all reports seriously - regardless of the age of the suspect.
He added: “The decision to arrest anyone, regardless of age, is never taken lightly and officers will always explore other options, where appropriate, to resolve a situation before taking a person into custody.”
“However, criminal offences can have a serious impact on their victims and arresting the suspect is often a necessity to effectively investigate a crime.”