Stray underwear soon turned into a full outfit, and before Williams knew it he had a box full of clothes that wasn't his.
With suspicions high and the neighbourhood on edge after the thefts, Williams soon caught his moggy cat Mo in the act.
Mo the cat has prowled the Mt Eden neighbourhood for two years, taking more than five box loads of clothing from unsuspecting residents. Photo / Supplied
"We saw Mo run across the road with a T-shirt in his mouth. We put two and two together that it was actually Mo bringing all the clothes over.
"We've had him for two years and it's been happening since day one."
During a two-year period, Mo had swiped up to five boxes' worth of clothing from the neighbourhood.
In May 2017, Williams outed his fur baby as neighbours speculated where their missing clothes had gone to and who the "perverted thief" was stealing all the underwear.
"Our cat is literally mental. Instead of bringing back dead birds, mice and other wildlife, Mo decides to bring home underwear and clothing, stolen from the neighbours' washing lines," Williams posted to Facebook.
"This is the THIRD haul of this size so far, and growing by the day ... Thank you for your service, kind sir!!"
Four months later with no 'paw-lice' in sight, Mo was back at it, terrorising the clotheslines of Mt Eden.
As the haul of underwear and other clothing items grew, it was time for Williams' second public service announcement.
Mo's stash from his crimes has included Calvin Klein underwear, t-shirts, pants, socks, undies, bras and other designer labelled clothing. Photo / Supplied
"With it being the start of summer..... And people having clothes on lines drying, Mo has started his new neighbourhood scour of underwear," Williams posted in October.
"We currently have a small selection of garments, but with more to come, undoubtedly. Mo is the king of the underwear theivery - will update as to his hauls as it happens."
Mo's stash included Calvin Klein underwear, lingerie, as well as numerous T-shirts, pants, socks and undies.
Fast forward to January 2018, and Mo's thieving paws had been up to no good again, reaching his fifth box load of clothes.
"It's been a busy month for my cat Mo! This is now the FIFTH box load of clothing he's retrieved from the local neighbourhood - all collected since I left Auckland at the start of December... I think he's actually getting better at this!!?
"Gotta love the big grey t-shirt - 'property of heavy lifting' printed on the front. So apt!!
"Good work mo!!!! (to my neighbour, if u see any of your clothing here, please pop around and collect it, as I literally have no idea where it all comes from... But I'm sure some will be yours - apologies for the inconvenience, but it is hella funny, innit?)"
During Mo's two-year terror of Mt Eden, residents have shown up to Williams' door justifiably frustrated.
"The neighbours are a bit annoyed. We've had a couple of people come around fairly irrate," Williams told the Herald.
"They've grown to love him after two years but they have to chase him off their property.
"He's pinching [clothing] off the clothesline during summer. So if anything is missing they know it's likely to be Mo so they come around and claim them.
"As soon as anyone puts anything up outside it's up for grabs, according to Mo."
Mt Eden residents suspected a 'creepy thief' had been stealing their underwear off the clothesline. That thief was Mo the cat. Photo / Supplied
Will Mo's reign of terror come to an end?
Williams doesn't seem to think so.
"He loves living with us. Maybe he just wants to reward us."
