[4] He began his career as a Boston-area musician, playing in bands such as Heretix, Chevy Heston, Jocobono, Left Nut, and Slower.

[13] He toured with Weezer beginning with their resurgence in the summer of 2000 and first appeared on their limited edition Christmas CD EP later that year (re-released in 2005 as Winter Weezerland).

In 2001, Welsh suffered a breakdown brought on by drug use, undiagnosed mental health problems, and the strain of touring.

I was in a coma for a few days, and woke up in a lockdown psychiatric ward.Weezer shot a new version of the video for their song "Island in the Sun" without Welsh.

[2] In an interview, he expressed his distaste for the corporate music process, stating that, "It's actually fun to just be playing in the studio without some major-label idiot standing over your shoulder.

[21] On September 2, 2010, he joined the band on stage at a show in Essex Junction, Vermont, to play bass on the song "Hash Pipe".

On July 29, 2011, Welsh played guitar on the song "Undone" with Weezer and the Flaming Lips at a show in New York.

Constructing creatures out of broken and dismantled chairs and furniture, to vacuum hoses, Tupperware, wire, and rope.

[25] On September 26, 2011, Welsh wrote on Twitter: "dreamt i died in chicago next weekend (heart attack in my sleep).

"[26] On October 8, 2011, Welsh was found dead in a Chicago hotel room from a suspected heroin overdose, leading to a heart attack.