story - Who stole my laptop?

It’s obvious that one of my “friends” was lying to me back in March this year. Someone who knew I’d be gone stole my $1,500 laptop and my crappy old broken microwave (I probably won’t ask for that one back).

I dug up this old chat log, hopefully you can tell me who’s full of it and who isn’t. You can assume only one person is/is aiding the thief, and everyone has perfect memory. Multiple backstabbers might just be too much for my fragile heart to handle.

4:11 PM  opened chat.
4:11 PM  joined chat.
4:11 PM  joined chat.
4:12 PM : hey alice
4:12 PM : hey, just back from your month in europe?
4:12 PM : a week ago, yeah, glad to be back in 'murica

4:12 PM  joined chat.
4:13 PM : sam, st patricks is tomorrow
4:13 PM : no **** alice im getting stoked early
4:14 PM : dude why we here anyway
4:15 PM : Wait until everyone gets here.
4:16 PM  joined chat.
4:16 PM : ssss
4:17 PM : hey scott how was europe with curmudgeon
4:18 PM : o didnt you hear? i had to stay home sick
4:18 PM : got ******* food poisoning like 2 days before the flight

4:18 PM : sucks to suck
4:19 PM : wheres john?
4:19 PM : said he’d be late, had a meeting or some ****
4:24 PM  joined chat.
4:25 PM : there he is, hurry up so my gf can paint me green
4:26 PM : okay guys, this might be a little uncomfortable, but I need you to answer honestly. I’m not going to sue or anything
4:26 PM : **** whats going on?
4:26 PM : hush up and listen john
4:27 PM : exactly one month ago, someone who knew my garage code got into my house and stole my laptop and microwave.
4:27 PM : you seriously think any of us would do that? wtf

4:28 PM : I wouldn’t be doing this if there weren’t a simple solution. since the culprit conveniently knocked over and broke my clock, which still displayed the date and time when I got home. I want all of you to tell me where you were at noon a month ago.
4:29 PM : were supposed to remember? i dont remember where i was 5 hours ago man
4:29 PM  Well thankfully, that was the day I called you all to see how you were doing, so you should have no trouble remembering.
4:30 PM : oh right, thats easy. i was still weak from the food poisoning and you called when i was mustering up the energy to go visit my man johnny
4:30 PM : i was probably at his house by noon
4:31 PM : you were, cause dude called me right before you got there and i told him to shove off
4:31 PM : can confirm, was told to shove off
4:31 PM : you called me while i was driving.
4:31 PM : yeah, i remember the roaring of the car when i called actually, it was hard to hear you
4:32 PM : was definitely still out around noon, since i grabbed a bite to eat

4:32 PM : i woke up, got ready, visited my grandma on one side of town, then back across to the post office to get stamps and mail a birthday card
4:32 PM : thanks. what about you sam?
4:33 PM : your call actually woke me up, after noon. i was asleep, man
4:33 PM : oh yeah, i remember that actually. sorry about that
4:34 PM : hey man, i saw sam that day around, walking down our street with his gf! dont bs me
4:34 PM : even if thats true, we dont live anywhere near curmudgeon, which means it couldnt have been me
4:35 PM : and while were on the topic, i know you werent with scott
4:35 PM : shut up sam
4:36 PM : he was with my gfs friend becca, probably stealing your microwave
4:37 PM : she doesnt live anywhere near him either and you know it

4:37 PM : fine sam, i made it up since my real alibi is so stupid. i was sound asleep at noon, i conked out right after i hung up with curmudgeon
4:38 PM : ya sorry, wouldnt have lied but i had to cover for this bumbling idiot
4:39 PM : idiots
4:39 PM : no, no guys, it’s okay, i believe all of you. was probably just somebody who watched me punch in the code sometime, it’s no big deal
4:40 PM : see you guys
4:40 PM  closed chat.

So maybe I’m a bit of an overbearing friend, but can you tell me if it paid off? Someone must have a contradiction in their story. Who’s lying? (There is a definitive answer, so don’t be too quick to flag this as "too broad" ye-who-likes-to-flag!)

Answer

The liar is

Alice

Because

She said she went to the post office. However, we know the chat conversation takes place the day before St Patrick's Day 2015, which means the 16th of March. The theft (and phone calls) occurred exactly 1 month previously, on Monday, February 16th. That was President's Day, which is a national holiday, so the post office would have been closed. Alice couldn't have bought stamps, so she must be lying.