The 'Cherry Pie' singer was found dead in his Woodland Hills hotel room on Thursday, but police said it was unclear how he had passed away.
An autopsy report released over the weekend also failed to determine what killed Lane, but toxicology tests have begun.
The singer's toxicology results are expected to be released within two months.
Lane struggled with alcohol addiction in the last several years of his life, with the musician being sentenced to jail time in July 2010 following a DUI conviction.
The Warrant frontman's sudden passing has drawn many tributes from the rock community.
Sugar Ray's Mark McGrath tweeted: "R.I.P. Jani Lane… a true songwriter and one of the most underrated voices in rock n roll, unfairly looked over because of hair metal tag."
Twisted Sister singer Dee Snider commented that he was deeply saddened by Lane's death, writing on Twitter: "Jani Lane's is yet another sad story of a boy who attained his dreams of greatness, only to be blindsided by the pressures, temptations and disappointments of those same dreams.
"We all watched over the years, as he soared, stumbled, fell, then got up again and again. Tragically, he will get up no more. RIP Jani."
Lane is survived by four siblings, two daughters and two step-daughters.
Watch Warrant's 'Cherry Pie' music video below: