Does A search warrant expire? And Can one be obtained by an anonymous call to the police?

With a C.I. and a detectives testimony of a transaction taking place in an alley behind a business (a supposed drug hand off)a search warrant was issued. Now if the transaction that was seen was a friend of mine handing me a sobe drink (found at any liquor store)and a hand shake saying"thanks 4...

Can a u.s. marshall enter and search someone's house without a search warrant, looking for someone that does not even live at that house?

My brother in law is in a state prison in California I visit him once a month. His family isn't allowed to visit due to visitation rights, they have traffic fines etc or unpaid citations. I guess they record everything over the phone and apparently my hubby and his brother were talking on the...

Someone drove by and saw a door open at my house, called the police and the police came and entered the house with no search warrant... are they allowed to enter with no search warrant without probable cause?