Here are the facts of the case. We live in an area that is 'not naice'. And we've pissed somebody off.
Lastnight, dp stepped out the front door for a vape... directly into a pile of fresh dog shit. We do not own a dog and do not open directly onto the street.
When he came in, he immediately said next door's dog had shat on our doorstep. Then bagged up his brand new socks and threw them in the bin 
He thinks it's next door because he's heard them complaining loudly about us vaping out the front 'a couple of times' apparently (first I've heard of it, I thought we were on good terms so why wouldn't she mention it if it was bothering her?). There aren't many dogs on our street so I see his point. Upsetting but Inspector EyerollChamp has a mystery to solve so must put personal feelings aside. So we have our first suspect: was it Mrs. 5 on the doorstep with the yappy chihuahua cross?
The next nearest dog owner is Mrs. 5's best bud, Mrs. 36. Mrs 36 is always out front with a fag hanging out of her mouth and wildly unbelievable tales of gossip about all and sundry. I had a massive falling out with her a few years back (entirely one-sided as she's one of those screaming in the street like a fish wife, no you can't have a word in edgeways types) over my son apparently threatening her (also keen on embellishments) dd with a used hypodermic needle. This story changed every time Mrs. 36 told it. First time, he had threatened her with it. 2nd he'd thrown it at her. 3rd he'd stabbed her with it 
Tried talking to her like an adult to get to the bottom of it but was shouted down every time. Then she seemingly quite arbitrarily started acting like it had never happened a few months later. Mrs 36 is very two-faced, arrogant, thick as mystery dog poo, nosy and brash.
So... was it number 36 on the doorstep with the grubby yet quite sweet poodle?
The plot thickens: Our other NDN, Mrs. 7, vacated the premises about 2 months ago on an unapproved mutual exchange. It was a sweet mercy for us. Mrs. 7 is a very loud, heroin and crystal meth addicted, extremely smelly and aggressive lady. And... she owns 7 CHIHUAHUAS. The number has varied slightly over the years as she's put them out to stud, or on a few occasions left them unattended while she went away for the weekend and come back to dead dogs. These dogs barked and howled constantly in her garden for nearly 3 years. Tried resolving it personally but had to get council involved and she was issued with a noise abatement order.
Mrs. 7 threw a massive rave before moving out purely, it would seem, as a fuck you to all the neighbours who had complained about her. Then her exchange was vetoed due to the damage she'd left and she was told to move back. She went 'fuck that' and absconded. But she's been back a couple of times to pick stuff up.
So... was it Mrs. 7 on the doorstep with a final fuck you?
Oh, and my ex husband has just moved into the flat opposite, next to Mrs. 36 
. He has literally shagged his way around the street and almost ended up back where he started.
So: AIBU to ask MN to help me solve this CFN mystery? Forensics are currently tied up solving murders and wotnot.