I eventually reported an incident to my manager after a guy I worked with kept harassing me.
Sorry that this is a little long winded.
It started that he followed me after work (going to public transport) by waiting for me to leave the office. I would try to avoid by hiding in the toilets until he'd gone. He made me feel very uncomfortable. Eventually one time I was walking with a friend, also from work, and stalker colleague suddenly stepped out from the shadows about 5 minutes away from work as he'd been waiting for me at the point where my friend and I divided to go our separate ways! He, unfortunately, went the same way I did.
He also borrowed money off me by pressurising me/guilt tripping me because he'd run out before pay day and didn't have money for the bus. Getting him to repay was difficult and awkward.
It all culminated in him inappropriately touching me. One day, he touched my leg in a very obvious way. I mean we were facing each other on office chairs as we worked in the same large double cubicle and had turned round from our desks to face each other. I had my legs crossed. We were talking about something to do with work and he suddenly sort of leant in and slowly stroked up my leg on the shin of my upper crossed leg. It was slow but also quick (in that I was not expecting it). He also didn't show he'd done it in his eyes or body language. It was freaky and made me feel so violated.
I asked to talk to my line manager who was also his LM. She believed me immediately. I told her about the other things and it turned out that other people has complained to her about him asking to borrow money off them and not paying it back easily. So, she sorted it all out. She had a word with him and moved me to a different desk/cubicle. I ignored him as much as was possible but was still civil.
I am glad I reported it. I would suggest doing what you said about talking to his LM, especially seeing as you are a manager yourself. I feel these men think that we won't say anything as we wonder if they did it or if people would believe us. It is also perhaps not the first time he's done it.