There may be many reasons you suspect this, you may have heard noises which have alarmed you or you may have seen incidents or injuries which have caused you suspicion. It can be very difficult to know what to do for the best in this situation, especially if you do not know the person well. You may feel reluctant to raise your concerns with your neighbour, you may feel it is none of your business, you may also fear that if you get involved it may exacerbate the situation.
It is important to remember your neighbour may be in danger. If you hear an incident and think your neighbour and any children living in the household are in danger, you could contact the police. If you are concerned for the safety and well being of the children, you could consider contacting your local Social Services team.
If you know your neighbour well, you could increase contact. You may find that as trust increases your neighbour may open up to you more. You can then encourage them to seek support in the ways outlined above.